Benzene derivatives and liquid-crystalline medium

ABSTRACT

A liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I ##STR1## in which R, Y, A 1 , A 2 , Z 1 , Z 2 , L 1  and m are as defined herein.

The present invention relates to benzene derivatives and to aliquid-crystalline medium, to the use of the latter for electroopticalpurposes, and to displays containing this medium.

Liquid crystals are used, in particular, as dielectrics in displaydevices since the optical properties of such substances can be affectedby an applied voltage. Electrooptical devices based on liquid crystalsare extremely well known to those skilled in the art and may be based onvarious effects. Devices of this type are, for example, cells havingdynamic scattering, DAP (deformation of aligned phases) cells,guest/host cells, TN cells having a twisted nematic structure, STN(super-twisted nematic) cells, SBE (super-birefringence effect) cellsand OMI (optical mode interference) cells. The most common displaydevices are based on the Schadt-Helfrich effect and have a twistednematic structure.

The liquid-crystal materials must have good chemical and thermalstability and good stability toward electrical fields andelectromagnetic radiation. Furthermore, the liquid-crystal materialsshould have low viscosity and give short addressing times, low thresholdvoltages and high contrast in the cells.

Furthermore, they should have a suitable mesophase, for example, for theabovementioned cells, a nematic or cholesteric mesophase, at customaryoperating temperatures, i.e. in the broadest possible range above andbelow room temperature. Since liquid crystals are generally used asmixtures of a plurality of components, it is important that thecomponents are readily miscible with one another. Further properties,such as electrical conductivity, dielectric anisotropy and opticalanisotropy, must meet various requirements depending on the cell typeand the area of application. For example, materials for cells having atwisted nematic structure should have positive dielectric anisotropy andlow electrical conductivity.

For example, the media desired for matrix liquid-crystal displayscontaining integrated nonlinear elements for switching individual imagepoints (MLC displays) are those having high positive dielectricanisotropy, broad nematic phases, relatively low birefringence, veryhigh specific resistance, good UV and temperature stability and a lowvapour pressure.

Matrix liquid-crystal displays of this type are known. Examples ofnonlinear elements which can be used to switch the individual imagepoints individually are active elements (i.e. transistors). This is thenreferred to as an "active matrix", and a differentiation can be madebetween two types:

1. MOS (Metal Oxide Semiconductor) or other diodes on a silicon wafer assubstrate.

2. Thin-film transistors (TFTs) on a glass plate as substrate.

The use of monocrystalline silicon as the substrate material limits thedisplay size since even the modular assembly of the various partdisplays results in problems at the joints.

In the case of the more promising type 2, which is preferred, theelectrooptical effect used is usually the TN effect. A differentiationis made between two technologies: TFTs comprising compoundsemiconductors, such as, for example, CdSe, or TFTs based onpolycrystalline or amorphous silicon. Intensive research efforts arebeing made worldwide in the latter technology.

The TFT matrix is applied to the inside of one glass plate of thedisplay, while the inside of the other glass plate carries thetransparent counter-electrode. Compared with the size of the image pointelectrode, the TFT is very small and hardly affects the image at all.This technology can also be extended to fully colour-compatible imagedisplays, where a mosaic of red, green and blue filters is arranged insuch a manner that each filter element is located opposite a switchableimage element.

The TFT displays usually operate as TN cells with crossed polarizers intransmission and are illuminated from the back.

The term MLC display here covers any matrix display containingintegrated nonlinear elements, i.e. in addition to the active matrix,also displays containing passive elements such as varistors or diodes(MIM=metal-insulator-metal).

MLC displays of this type are particularly suitable for TV applications(for example pocket TV sets) or for high-information displays forcomputer applications (laptops) and in automobile or aircraftconstruction. In addition to problems with respect to the angledependency of the contrast and the switching times, problems result inMLC displays due to inadequate specific resistance of the liquid-crystalmixtures [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E.,SORIMACHI, K., TAJIMA, E., WATANBE, H., SHIMIZU, H., Proc. Eurodisplay84, September 1984: A 210-288, Matrix LCD Controlled by Double StageDiode Rings, p. 141 ff., Paris; STROMER, M., Proc. Eurodisplay 84,September 1984: Design of Thin Film Transistors for Matrix Adressing ofTelevision Liquid Crystal Displays, p. 145 ff., Paris]. As theresistance decreases, the contrast of an MLC display worsens and theproblem of "after-image elimination" may occur. Since the specificresistance of the liquid-crystal mixture generally decreases over thelife of an MLC display due to interaction with the internal surfaces ofthe display, a high (initial) resistance is very important to giveacceptable service lives. In particular in the case of low-voltagemixtures, it was hitherto not possible to achieve very high specificresistances. It is furthermore important that the specific resistanceincreases as little as possible with increasing temperature and afterheating and/or exposure to UV radiation. The low-temperature propertiesof the mixtures from the prior art are also particularlydisadvantageous. It is required that crystallization and/or smecticphases do not occur, even at low temperatures, and that the temperaturedependence of the viscosity is as low as possible. The MLC displays ofthe prior art thus do not satisfy current demands.

Thus, there continues to be a great demand for MLC displays of very highspecific resistance and at the same time a broad operating temperaturerange, short switching times, even at low temperatures and low thresholdvoltage which do not have these disadvantages or only do so to a lesserextent.

For TN (Schadt-Helfrich) cells, media are desired which facilitate thefollowing advantages in the cells:

broadened nematic phase range (in particular down to low temperatures),

switchability at extremely low temperatures (outdoor use, automobiles,avionics),

increased stability to UV radiation (longer life).

The media available from the prior art do not make it possible toachieve these advantages whilst simultaneously retaining the otherparameters.

For supertwisted (STN) cells, media are desired which allow a greatermultiplexing ability and/or lower threshold voltages and/or broadernematic phase ranges (in particular at low temperatures). To this end, afurther extension of the parameter latitude available (clearing point,smectic-nematic transition or melting point, viscosity, dielectricvalues, elastic values) is urgently desired.

The invention has the object of providing media, in particular for MLC,TN or STN displays of this type, which do not have the abovementioneddisadvantages or only do so to a lesser extent, and preferably at thesame time have very high specific resistances and low thresholdvoltages.

It has now been found that this object can be achieved if mediaaccording to the invention are used in displays.

The invention thus relates to a liquid-crystal-line medium based on amixture of polar compounds having positive dielectric anisotropy,characterized in that it contains one or more compounds of the generalformula I ##STR2## in which

R is H, an alkyl or alkenyl radical having 1 to 15 carbon atoms which isunsubstituted, monosubstituted by CN or CF₃ or at least monosubstitutedby halogen, it also being possible for one or more CH₂ groups in theseradicals to be replaced, in each case independently of one another, by--O--, --S--, ##STR3## CO--, --CO--O--, --O--CO-- or --O--CO--O-- insuch a way that O atoms are not linked directly to one another,

A¹ and A² are each, independently of one another, atrans-1,4-cyclohexylene radical in which, in addition, one or morenon-adjacent CH₂ groups may be replaced by --O-- and/or --S--, or acyclohexenylene radical,

Z¹ and Z² are each, independently of one another, --CO--O--, --O--CO--,--CH₂ O--, --OCH₂ --, --CH₂ CH₂ --, --CH═CH--, --C.tbd.C-- or a singlebond, and one of the radicals Z¹ and Z² is alternatively --(CH₂)₄ -- or--CH--CH--CH₂ CH₂ --,

Y is F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 carbonatoms,

L¹ is H or F, and

m is 0 or 1.

The compounds of the formula I have a broad range of applications.Depending on the choice of substituents, these compounds can be used asbase materials from which liquid-crystalline materials are predominantlycomposed; however, compounds of the formula I can also be added toliquid-crystalline base materials from other classes of compounds, inorder, for example, to modify the dielectric and/or optical anisotropyof a dielectric of this type and/or to optimize its threshold voltageand/or its viscosity.

In the pure state, the compounds of the formula I are colourless andform liquid-crystalline mesophases in a temperature range which isfavourably located for electro-optical use. They are stable chemically,thermally and to light.

Compounds of the formula ##STR4## in which X is F, Cl, CF₃, CHF₂, OCHF₂or OCF₃, r is 0 or 1, Z is H or F, and the ring A is 1,4-cyclohexyleneor 1,4-phenylene have already been disclosed in WO 91-13850.

The invention also relates to the compounds of the formula I in which L¹is H and the radical Y contains at least two carbon atoms.

In the media according to the invention containing compounds of theformula I, Y is preferably F, Cl, OCF₃, OCHF₂, CF₃, CHFCF₃, CF₂ CHF₂, C₂H₄ CHF₂, CF₂ CH₂ CF₃, CHF₂, OCH₂ CF₃, OCH₂ CHF₂, OCF₂ CHF₂, O(CH₂)₃ CF₃,OCH₂ C₂ F₅, OCH₂ CF₂ CHF₂, OCH₂ C₃ F₇, OCHFCF₃, OC₂ F₅, OCF₂ CHFCF₃,OCH═CF₂, OCF═CF₂, OCF═CFCF₃, OCF═CF--C₂ FS, CH═CHF, CH═CF₂, CF═CF₂, CF₂OCF₃, in particular F, OCHFCF₃, OCF₃, OCHF₂, OC₂ F₅, OC₃ F₇, OCH═CF₂, orCF₂ OCF₃.

Particular preference is given to compounds of the formula I in which L¹is H and/or m is 0.

Z¹ and Z² are preferably a single bond and --CH₂ CH₂ --, secondarilypreferably --CH₂ O--, --OCH₂ --, --O--CO-- and --CO--O--.

If one of the radicals Z¹ and Z² is --(CH₂)₄ -- or --CH═CH--CH₂ CH₂ --,the other radical Z¹ or Z² (if present) is preferably the single bond.

If R is an alkyl radical and/or an alkoxy radical, this may bestraight-chain or branched. It is preferably straight-chain, has 2, 3,4, 5, 6 or 7 carbon atoms and accordingly is preferably ethyl, propyl,butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxyor heptoxy, furthermore methyl, octyl, nonyl, decyl, undecyl, dodecyl,tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, nonoxy, decoxy,undecoxy, dodecoxy, tridecoxy or tetradecoxy.

Oxaalkyl is preferably straight-chain 2-oxapropyl (═methoxymethyl),2-(═ethoxymethyl) or 3-oxabutyl (═2-methoxyethyl), 2-, 3- or4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl,2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl,or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

If R is an alkyl radical in which one CH₂ group has been replaced by--CH═CH--, this may be straight-chain or branched. It is preferablystraight-chain and has 2 to 10 carbon atoms. It is accordingly inparticular vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-,-2-, -3- or -4-enyl, hex-l-, -2-, -3-, -4- or -5- enyl, hept-1-, -2-,-3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl,non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, or dec-1-, -2-, -3-,-4-, -5-, -6-, -7-, -8- or -9-enyl.

If R is an alkyl radical in which one CH₂ group has been replaced by--O-- and one has been replaced by --CO--, these are preferablyadjacent. These thus contain an acyloxy group --CO--O-- or anoxycarbonyl group --O--CO--. These are preferably straight-chain andhave 2 to 6 carbon atoms.

They are accordingly in particular acetoxy, propionyloxy, butyryloxy,pentanoyloxy, hexanoyloxy, acetoxymethyl, propionyloxymethyl,butyryloxymethyl, pentanoyloxymethyl, 2-acetoxyethyl,2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetoxypropyl,3-propionyloxypropyl, 4-acetoxybutyl, methoxycarbonyl, ethoxycarbonyl,propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl,ethoxycarbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl,2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl,2-(propoxycarbonyl)ethyl, 3-(methoxycarbonyl)propyl,3-(ethoxycarbonyl)propyl or 4-(methoxycarbonyl)butyl.

If R is an alkyl radical in which one CH₂ group has been replaced byunsubstituted or substituted --CH═CH-- and an adjacent CH₂ group hasbeen replaced by CO or CO--O or O--CO, this may be straight-chain orbranched. It is preferably straight-chain and has 4 to 13 carbon atoms.It is accordingly in particular acryloyloxymethyl, 2-acryloyloxyethyl,3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl,6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl,9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryloyloxymethyl,2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl,5-methacryloyloxypentyl, 6-methacryloyloxyhexyl,7-methacryloyloxyheptyl, 8-methacryloyloxyoctyl or9-methacryloyloxynonyl.

If R is an alkyl or alkenyl radical which is monosubstituted by CN orCF₃, this radical is preferably straight-chain. The substitution by CNor CF₃ is in any desired position.

If R is an alkyl or alkenyl radical which is at least monosubstituted byhalogen, this radical is preferably straight-chain and halogen ispreferably F or Cl. In the case of multiple substitution, halogen ispreferably F. The resulting radicals also include perfluorinatedradicals. In the case of monosubstitution, the fluorine or chlorinesubstituent may be in any desired position, but is preferably in theω-position.

Compounds of the formula I which contain wing groups R which aresuitable for polymerization reactions are suitable for the preparationof liquid-crystalline polymers.

Compounds of the formula I containing branched wing groups R mayoccasionally be of importance due to better solubility in the customaryliquid-crystalline base materials, but in particular as chiral dopes ifthey are optically active. Smectic compounds of this type are suitableas components of ferroelectric materials.

Compounds of the formula I having S_(A) phases are suitable, forexample, for thermally addressed displays.

Branched groups of this type generally contain not more than one chainbranch. Preferred branched radicals R are isopropyl, 2-butyl(═1-methylpropyl), isobutyl (═2-methylpropyl), 2-methylbutyl, isopentyl(═3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl,2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy,3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy,1-methylhexoxy and 1-methylheptoxy.

If R is an alkyl radical in which two or more CH₂ groups have beenreplaced by --O-- and/or --CO--O--, this may be straight-chain orbranched. It is preferably branched and has 3 to 12 carbon atoms. It isaccordingly in particular biscarboxymethyl, 2,2-biscarboxyethyl,3,3-biscarboxypropyl, 4,4-biscarboxybutyl, 5,5-biscarboxypentyl,6,6-biscarboxyhexyl, 7,7-biscarboxyheptyl, 8,8-biscarboxyoctyl,9,9-biscarboxynonyl, 10,10-biscarboxydecyl, bis(methoxycarbonyl)methyl,2,2-bis(methoxycarbonyl)ethyl, 3,3-bis(methoxycarbonyl)propyl,4,4-bis(methoxycarbonyl)butyl, 5,5-bis(methoxycarbonyl)pentyl,6,6-bis(methoxycarbonyl)hexyl, 7,7-bis(methoxycarbonyl)heptyl,8,8-bis(methoxycarbonyl)octyl, bis(ethoxycarbonyl)methyl,2,2-bis(ethoxycarbonyl)ethyl, 3,3-bis(ethoxycarbonyl)propyl,4,4-bis(ethoxycarbonyl)butyl or 5,5-bis(ethoxycarbonyl)hexyl.

Preferred smaller groups of compounds of the formula I are those of thesubformulae I1 to I6 [L¹ =H or F]: ##STR5## Particular preference isgiven to the compounds of the formulae I1 and I2.

The 1,4-cyclohexenylene group preferably has the following structures:##STR6##

The compounds of the formula I are prepared by methods known per se, asdescribed in the literature (for example in the standard works, such asHouben-Weyl, Methoden der Organischen Chemie, Georg-Thieme-Verlag,Stuttgart), to be precise under reaction conditions which are known andsuitable for said reactions. Use may also be made here of variants whichare known per se, but are not described here in greater detail.

The compounds according to the invention can be prepared, for example,by metallating a compound of formula II ##STR7## in which R, A¹, A², Z¹,Z², L¹ and m are as defined above, and subsequently reacting the productwith a suitable electrophile, or by a coupling reaction as follows:##STR8##

Particularly preferred compounds of the formula I are prepared, forexample, as follows: ##STR9##

The invention also relates to electrooptical displays (in particular STNor MLC displays having two plane-parallel outer plates which, togetherwith a frame, form a cell, integrated nonlinear elements for switchingindividual image points on the outer plates, and a nematicliquid-crystal mixture of positive dielectric anisotropy and highspecific resistance located in the cell) which contain media of thistype, and to the use of these media for electrooptical purposes.

The liquid-crystal mixtures according to the invention facilitate asignificant broadening of the parameter latitude available.

The achievable combinations of clearing point, viscosity at lowtemperature, thermal and UV stability and dielectric anisotropy are farsuperior to the previous materials from the prior art.

The requirement for a high clearing point, a nematic phase at lowtemperature and a high As was previously only achievable to anunsatisfactory extent. Although systems such as, for example, ZLI-3119have a comparable clearing point and comparatively favourableviscosities, they have, however, a Δε of only +3.

Other mixture systems have comparable viscosities and values of Δε, butonly have clearing points in the region of 60° C.

The liquid-crystal mixtures according to the invention make it possible,while retaining the nematic phase at down to -20° C. and preferably downto -30° C., particularly preferably down to -40° C., to achieve clearingpoints above 80°, preferably above 90°, particularly preferably above100° C., simultaneously dielectric anisotropy values Δε≧6, preferably≧8, and a high value for the specific resistance, which means thatexcellent STN and MLC displays can be achieved. The mixtures arecharacterized in particular by low operating voltages. The TN thresholds(VIP) are below 2.0 V, preferably below 1.5 V, particularly preferably<1.3 V.

It goes without saying that a suitable choice of the components of themixtures according to the invention also allows higher clearing points(for example above 110°) to be achieved at higher threshold voltages orlower clearing points to be achieved at lower threshold voltages whileretaining the other advantageous properties. It is likewise possible toobtain mixtures of relatively high Δε and thus lower thresholds if theviscosities are increased by a correspondingly small amount. The MLCdisplays according to the invention preferably operate in the firsttransmission minimum of Gooch and Tarry [C. H. Gooch and H. A. Tarry,Electron. Lett. 10, 2-4, 1974; C. H. Gooch and H. A. Tarry, Appl. Phys.,Vol. 8, 1575-1584, 1975]; in this case, a lower dielectric anisotropy inthe second minimum is sufficient in addition to particularly favourableelectrooptical properties, such as, for example, high gradient of thecharacteristic line and low angle dependency of the contrast (GermanPatent 30 22 818) at the same threshold voltage as in an analogousdisplay. This allows significantly higher specific resistances to beachieved in the first minimum using the mixtures according to theinvention than using mixtures containing cyano compounds. A personskilled in the art can use simple routine methods to produce thebirefringence necessary for a prespecified layer thickness of the MLCdisplay by a suitable choice of the individual components and theirproportions by weight.

The viscosity at 20° C. is preferably <60 mpa.s, particularly preferably<50 mPa.s. The nematic phase range is preferably at least 90°, inparticular at least 100°. This range preferably extends at least from-20° to +80°.

Measurements of the "capacity holding ratio" (HR) [S. Matsumoto et al.,Liquid Crystals 5, 1320 (1989); K. Niwa et al., Proc. SID Conference,San Francisco, June 1984, p. 304 (1984); G. Weber et al., LiquidCrystals 5, 1381 (1989)] have shown that mixtures according to theinvention containing compounds of the formula I exhibit a considerablysmaller decrease in the HR with increasing temperature than do analogousmixtures in which the compounds of the formula I are replaced bycyanophenylcyclohexanes of the formula ##STR10## or esters of theformula ##STR11##

The UV stability of the mixtures according to the invention is alsoconsiderably better, i.e. they exhibit a significantly smaller decreasein the HR on exposure to UV radiation.

The media according to the invention are preferably based on a plurality(preferably two or more) of compounds of the formula I, i.e. theproportion of these compounds is 5-95%, preferably 10-60% andparticularly preferably in the range 20-50%.

The individual compounds of the formulae I to XII and their subformulaewhich can be used in the media according to the invention are eitherknown or can be prepared analogously to the known compounds.

Preferred embodiments are indicated below:

medium contains compounds of the formula I, wherein R is preferablyethyl, secondarily preferably propyl, butyl and pentyl. The thresholdvoltage of LC mixtures can be reduced in an effective manner byutilizing shorter terminal alkyl chains of polar compounds then longerones. An ethyl chain is more effective for V_(th) then a propyl orpentyl chain and this effect results from the reduction of the elasticproperties.

medium additionally contains one or more compounds selected from thegroup comprising the general formulae II to VI: ##STR12## in which theindividual radicals are as defined below:

R⁰ : n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having upto 9 carbon atoms,

X⁰ : F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 carbonatoms,

Y¹ and

Y² : each, independently of one another, H or F,

r: 0 or 1,

with the proviso that the compounds III and IV are not identical to thecompounds of the formula I.

The compound of the formula IV is preferably ##STR13## mediumadditionally contains one or more compounds of the formula ##STR14##medium additionally contains one or more compounds selected from thegroup consisting of the general formulae VII to XII: ##STR15## in whichR⁰, X⁰, Y¹ and Y² are each, independently of one another, as defined inclaim 2, preferably is F, Cl, CF₃, OCF₃, OCHF₂, alkyl, oxaalkyl,fluoroalkyl or alkenyl, in each case having up to 6 carbon atoms.

the proportion of compounds of the formulae I to VI together in thetotal mixture is at least 50% by weight

the proportion of compounds of the formula I in the total mixture isfrom 10 to 50% by weight

the proportion of compounds of the formulae II to VI in the totalmixture is from 30 to 70% by weight ##STR16## the medium containscompounds of the formulae II, III, IV, V or VI R⁰ is straight-chainalkyl or alkenyl having 2 to 7 carbon atoms

the medium essentially comprises compounds of the formulae I to VI

the medium contains further compounds, preferably selected from thefollowing group consisting of the general formulae XIII to XVI:##STR17## in which R⁰ and X⁰ are as defined above and the 1,4-phenylenerings may be substituted by CN, chlorine or fluorine. The 1,4-phenylenerings are preferably mono- or polysubstituted by fluorine atoms.

the I:(II+III+IV+V+VI) weight ratio is preferably from 1:10 to 10:1.

medium essentially comprises compounds selected from the groupconsisting of the general formulae I to XII.

It has been found that even a relatively small proportion of compoundsof the formula I mixed with conventional liquid-crystal materials, butin particular with one or more compounds of the formula II, III, IV, Vand/or VI, results in a significant lowering of the threshold voltageand in low values for the birefringence, and at the same time broadnematic phases with low smectic-nematic transition temperatures areobserved, as a result of which the shelf life is improved. The compoundsof the formulae I to VI are colourless, stable and readily miscible withone another and with other liquid-crystal materials.

The term "alkyl" covers straight-chain and branched alkyl groups having1-7 carbon atoms, in particular the straight-chain groups methyl, ethyl,propyl, butyl, pentyl, hexyl and heptyl. Groups having 2-5 carbon atomsare generally preferred.

The term "alkenyl" covers straight-chain and branched alkenyl groupshaving 2-7 carbon atoms, in particular the straight-chain groups.Preferred alkenyl groups are C₂ -C₇ -1E-alkenyl, C₄ -C₇ -3E-alkenyl, C₅-C₇ -4-alkenyl, C₆ -C₇ -5-alkenyl and C₇ -6-alkenyl, in particular C₂-C₇ -1E-alkenyl, C₄ -C₇ -3E-alkenyl and C₅ -C₇ -4-alkenyl. Examples ofpreferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl,1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl,3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl,4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups having up to 5carbon atoms are generally preferred.

The term "fluoroalkyl" preferably covers straight-chain groupscontaining terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl,3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and7-fluoroheptyl. However, other positions of the fluorine are notexcluded.

The term "oxaalkyl" preferably covers straight-chain radicals of theformula C_(n) H_(2n+1) --O--(CH₂)_(m), in which n and m are each,independently of one another, from 1 to 6. n is preferably 1 and m ispreferably from 1 to 6.

Through a suitable choice of the meanings of R⁰ and X⁰, the addressingtimes, the threshold voltage, the gradient of the transmissioncharacteristic lines, etc., can be modified as desired. For example,1E-alkenyl radicals, 3E-alkenyl radicals, 2E-alkenyloxy radicals and thelike generally give shorter addressing times, improved nematictendencies and a higher ratio between the elastic constants k₃₃ (bend)and k₁₁ (splay) compared with alkyl and alkoxy radicals. 4-Alkenylradicals, 3-alkenyl radicals and the like generally give lower thresholdvoltages and lower values of k₃₃ /k₁₁ compared with alkyl and alkoxyradicals.

A --CH₂ CH₂ -- group in Z² generally results in higher values of k₃₃/k₁₁ compared with a simple covalent bond. Higher values of k₃₃ /k₁₁facilitate, for example, flatter transmission characteristic lines in TNcells with a 90° twist (for achieving grey tones) and steepertransmission characteristic lines in STN, SBE and OMI cells (greatermultiplexing ability), and vice versa.

The optimum mixing ratio of the compounds of the formulae I andII+III+IV+V+VI depends substantially on the desired properties, on thechoice of the components of the formulae I, II, III, IV, V and/or VI andon the choice of any other components which may be present. Suitablemixing ratios within the abovementioned range can easily be determinedfrom case to case.

The total amount of compounds of the formulae I to XII in the mixturesaccording to the invention is not crucial. The mixtures may thereforecontain one or more further components in order to optimize variousproperties. However, the effect observed on the addressing times and thethreshold voltage is generally greater the higher the totalconcentration of compounds of the formulae I to XII.

In a particularly preferred embodiment, the media according to theinvention contain compounds of the formulae II to VI (preferably IIand/or III) in which X⁰ is OCF₃, OCHF₂, F, OCH═CF₂, OCF═CF₂ or OCF₂ --F₂H. A favourable synergistic effect with the compounds of the formula Iresults in particularly advantageous properties.

The construction of the MLC display according to the invention frompolarizers, electrode baseplates and electrodes with surface treatmentcorresponds to the construction which is conventional for displays ofthis type. The term conventional construction here is widely drawn andalso covers all derivatives and modifications of the MLC display, inparticular also matrix display elements based on poly-Si TFTs or MIMs.

An essential difference between the displays according to the inventionand those customary hitherto based on the twisted nematic cell is,however, the choice of liquid-crystal parameters in the liquid-crystallayer.

The liquid-crystal mixtures which can be used according to the inventionare prepared in a manner which is conventional per se. In general, thedesired amount of the components used in the lesser amount is dissolvedin the components making up the principal constituents, expediently atelevated temperature. It is also possible to mix solutions of thecomponents in an organic solvent, for example in acetone, chloroform ormethanol, and, after thorough mixing, to remove the solvent again, forexample by distillation.

The dielectrics may also contain other additives known to those skilledin the art and described in the literature. For example, 0-15% ofpleochroic dyes or chiral dopes can be added.

C denotes a crystalline phase, S a smectic phase, S_(c) a smectic Cphase, N a nematic phase and I the isotropic phase.

V₁₀ denotes the voltage for 10% transmission (view angle perpendicularto the plate surface). t_(on) denotes the switch-on time and t_(off) theswitch-off time at an operating voltage corresponding to 2.5 times thevalue of V₁₀. Δn denotes the optical anisotropy and n₀ the refractiveindex. Δε denotes the dielectric anisotropy (Δε=ε.sub.∥ -ε₁₉₅ , whereε₈₁ is the dielectric constant parallel to the longitudinal molecularaxes and ε.sub.⊥ is the dielectric constant perpendicular thereto). Theelectrooptical data were measured in a TN cell at the 1st minimum (i.e.at a d·Δn value of 0.5) at 20° C., unless expressly stated otherwise.The optical data were measured at 20° C., unless expressly statedotherwise.

In the present application and in the examples below, the structures ofthe liquid-crystal compounds are indicated by acronyms, with thetransformation into chemical formulae taking place in accordance withTables A and B below. All radicals C_(n) H_(2n+1) and C_(m) H_(2m+1) arestraight-chain alkyl radicals containing n or m carbon atoms. The codingin Table B is self-evident. In Table A, only the acronym for the basestructure is given. In individual cases, the acronym for the basestructure is followed, separated by a hyphen, by a code for thesubstituents R¹, R², L¹ and L² :

    ______________________________________                                        Code for R.sup.1,                                                               R.sup.2, L.sup.1, L.sup.2 R.sup.1 R.sup.2 L.sup.1 L.sup.2                   ______________________________________                                        nm      C.sub.n H.sub.2n+1                                                                              C.sub.m H.sub.2m+1                                                                       H   H                                      nOm C.sub.n H.sub.2n+1 OC.sub.m H.sub.2m+1 H H                                nO.m OC.sub.n H.sub.2n+1 C.sub.m H.sub.2m+1 H H                               n C.sub.n H.sub.2n+1 CN H H                                                   nN.F C.sub.n H.sub.2n+1 CN H F                                                nF C.sub.n H.sub.2n+1 F H H                                                   nOF OC.sub.n H.sub.2n+1 F H H                                                 nCl C.sub.n H.sub.2n+1 Cl H H                                                 nF.F C.sub.n H.sub.2n+1 F H F                                                 nF.F.F C.sub.n H.sub.2n+1 F F F                                               nCF.sub.3 C.sub.n H.sub.2n+1 CF.sub.3 H H                                     nOCF.sub.3 C.sub.n H.sub.2n+1 OCF.sub.3 H H                                   nOCF.sub.2 C.sub.n H.sub.2n+1 OCHF.sub.2 H H                                  nS C.sub.n H.sub.2n+1 NCS H H                                                 rVsN C.sub.r H.sub.2r+1 --CH═CH--C.sub.s H.sub.2s -- CN H H                                                       rEsN C.sub.r H.sub.2r+1                                                      --O--C.sub.2 H.sub.2s -- CN H H                                                nAm C.sub.n H.sub.2n+1 COOC.sub.                                             m H.sub.2m+1 H H                       nOCCF.sub.2.F.F C.sub.n H.sub.2n+1 OCH.sub.2 CF.sub.2 H F F                 ______________________________________                                    

Preferred mixture components are shown in Tables A and B.

                  TABLE A                                                         ______________________________________                                          #STR18##                                                                       -                                                                            #STR19##                                                                       -                                                                            #STR20##                                                                       -                                                                            #STR21##                                                                       -                                                                            #STR22##                                                                       -                                                                            #STR23##                                                                       -                                                                            #STR24##                                                                       -                                                                            #STR25##                                                                       -                                                                            #STR26##                                                                       -                                                                            #STR27##                                                                       -                                                                            #STR28##                                                                       -                                                                            #STR29##                                                                       -                                                                            #STR30##                                                                       -                                                                            #STR31##                                                                       -                                                                            #STR32##                                                                       -                                                                            #STR33##                                                                       -                                                                            #STR34##                                                                       -                                                                            #STR35##                                                                       -                                                                            #STR36##                                                                       -                                                                            #STR37##                                                                       -                                                                            #STR38##                                                                    ______________________________________                                    

                                      TABLE B                                     __________________________________________________________________________      #STR39##                                                                       -                                                                            #STR40##                                                                       -                                                                            #STR41##                                                                       -                                                                            #STR42##                                                                       -                                                                            #STR43##                                                                       -                                                                            #STR44##                                                                       -                                                                            #STR45##                                                                       -                                                                            #STR46##                                                                       -                                                                            #STR47##                                                                       -                                                                            #STR48##                                                                       -                                                                            #STR49##                                                                       -                                                                            #STR50##                                                                       -                                                                            #STR51##                                                                       -                                                                            #STR52##                                                                       -                                                                            #STR53##                                                                       -                                                                            #STR54##                                                                       -                                                                            #STR55##                                                                       -                                                                            #STR56##                                                                       -                                                                            #STR57##                                                                    __________________________________________________________________________

The examples below are intended to illustrate the invention withoutpresenting a limitation. Above and below, percentages are by weight. Alltemperatures are given in degrees Celsius. m.p. denotes melting point,c.p.=clearing point. Furthermore, C=crystalline state, N=nematic phase,S=smectic phase and I=isotropic phase. The numbers between these symbolsrepresent the transition temperatures. Δn denotes optical anisotropy(589 nm, 20° C.) and the viscosity (mm² /sec) was determined at 20° C.

"Conventional work-up" means that, if necesary, water is added, themixture is extracted with dichloromethane, diethyl ether, methyltert-butyl ether or toluene, the organic phase is separated off, driedand evaporated, and the product is purified by distillation underreduced pressure or crystallization and/or chromatography. The followingabbreviations are used:

    ______________________________________                                        DMEU           1,3-dimethyl-2-imidazolidinone                                   POT potassium tertiary-butoxide                                               THF tetrahydrofuran                                                           pTSOH p-toluenesulphonic acid                                               ______________________________________                                    

EXAMPLE 1 ##STR58## Step 1.1 ##STR59##

1.32 mol of n-butyllithium (15% in n-hexane) are added dropwise over thecourse of 1 hour at -100° C. in a nitrogen atmosphere to 1.2 mol of4-(trans-4-propylcyclohexyl)-2-fluorobenzene, 1.2 mol of potassiumtert-butoxide and 3 l of THF. The mixture is stirred for a further 1hour, and 1.38 mol of trimethyl borate are added dropwise to thereaction mixture at -100° C., and the mixture is stirred for a further1.5 hours. 3.6 l of 18% HCl are added, the organic phase is separatedoff, and the aqueous phase is extracted with toluene. The combinedorganic extracts are subsequently subjected to a conventional work-up.

Step 1.2 ##STR60##

1.6 g of tetrakis(triphenylphosphine)palladium-(0) and a sodiumcarbonate solution (41.66 g of Na₂ CO₃ in 150 ml of H₂ O) are added to0.13 mol of 4-(trans-4-propylcyclohexyl)-2-fluorophenylboronic acid,0.13 mol of 2,3,4-trifluorobromobenzene, 325 ml of toluene and 130 ml ofethanol. The mixture is allowed to cool to room temperature, and theorganic phase is separated off. The aqueous phase is extracted withtoluene, and the combined organic extracts are subsequently subjected toconventional work-up. C 42 N 57.1 I; Δn+0.131; Δε=10.01.

The following compounds of the formula ##STR61## are preparedanalogously:

    ______________________________________                                        R         Y     L.sup.1                                                       ______________________________________                                        CH.sub.3  F     H                                                               CH.sub.3 F F                                                                  C.sub.2 H.sub.5 F H C 36 N (-1,9) I; Δn = +0,112;                          Δε = 8,86                                                    C.sub.2 H.sub.5 F F C 55 I; Δn = +0,104; Δε = 15,03       n-C.sub.3 H.sub.7 F F C 64 I; Δn = +0,117; Δε =                                   14,02                                                 n-C.sub.5 H.sub.11 F H C 35 N 73,9 I; Δn = +0,124;                         Δε = 9,68                                                    n-C.sub.5 H.sub.11 F F C 63 N (37.0) I; Δn = +0,114;                       Δε = 13,76                                                   n-C.sub.6 H.sub.13 F H                                                        n-C.sub.6 H.sub.13 F F                                                        n-C.sub.3 H.sub.7 Cl H                                                        n-C.sub.3 H.sub.7 Cl F                                                        n-C.sub.5 H.sub.11 Cl H C 66 N 112,1 I; Δn = +0,166;                       Δε = 11,19                                                   n-C.sub.5 H.sub.11 Cl F                                                     ______________________________________                                    

EXAMPLE 2 ##STR62## Step 2.1 ##STR63##

1.0 mol of sodium hydride (60%) is suspended in 200 ml of THF undernitrogen, and 1.0 mol of 4-bromo-2-fluorophenol, dissolved in 400 ml ofTHF, is added dropwise at 0° C. The mixture is allowed to warm to roomtemperature, stirred for 0.5 hour and filtered. The filtrate isevaporated, dissolved in toluene and evaporated to inducecrystallization. The residue is precipitated using petroleum ether. Thecrystals are filtered off with suction and dried.

Step 2.2 ##STR64##

0.08 mol of the phenoxide from 2.1 is introduced into 80 ml of DMEU, andthe mixture is heated to 50° C. 0.088 mol of1,2,2,2-tetrafluoro-1-iodoethane is added, and the mixture is stirred at50° C. for 16 hours. The mixture is allowed to cool to room temperatureand water is added. The mixture is acidified using dilute HCl, extractedwith methyl tert-butyl ether, then with 10% NaOH and water, dried overNa₂ SO₄ and filtered. The filtrate is evaporated and distilled at 800mbar in a bulb tube.

Step 2.3 ##STR65##

0.013 mol of 1-(1,2,2,2-tetrafluoroethoxy)-2-fluoro-4-bromobenzene aredissolved in 50 ml of THF, the solution is heated to 60° C., and 0.012mol of 4-(trans-4-propylcyclohexyl)-2-fluorophenylboronic acid and asolution comprising 0.013 mol of KH₂ PO₄, 0.025 mol of Na₂ HPO₄ and 25ml of water are added. 0.012 mol oftetrakis(triphenylphosphine)palladium(0) is added, and the mixture isstirred at 70° C. overnight. The mixture is allowed to cool to roomtemperature and is subjected to conventional work-up. C 15 N 103.2 I;Δn=0.128; Δε=16.78

The following compounds of the formula ##STR66## are preparedanalogously:

    ______________________________________                                        (A                                                                            .sup.1 - Z.sup.1).sub.m -A.sup.2 - Z.sup.2 -                                                          L.sup.1                                               ______________________________________                                          C.sub.2 H.sub.5                                                                                             H TR67##                                         - C.sub.2 H.sub.5                                                                                          F C 52 N (50.0) I; Δn =  +0.117;                                      Δε =20.18                            - n-C.sub.3 H.sub.7                                                                                        F C 71 N 89.4 I; Δn =  0.129;                                         Δε = 18.95                           - n-C.sub.4 H.sub.9                                                                                        H TR70##                                         - n-C.sub.4 H.sub.9                                                                                        F TR71##                                         - n-C.sub.5 H.sub.11                                                                                       H TR72##                                         - n-C.sub.5 H.sub.11                                                                                       F C 52 N 96.9 I; Δn =  +0.127;                                        Δε = 18.47                           - n-C.sub.6 H.sub.13                                                                                       H TR74##                                         - n-C.sub.6 H.sub.13                                                                                       F TR75##                                         - C.sub.2 H.sub.5                                                                                          H TR76##                                         - C.sub.2 H.sub.5                                                                                          F TR77##                                         - n-C.sub.3 H.sub.7                                                                                        H TR78##                                         - n-C.sub.3 H.sub.7                                                                                        F TR79##                                         - n-C.sub.5 H.sub.11                                                                                       H TR80##                                         - n-C.sub.5 H.sub.11                                                                                       FSTR81##                                      ______________________________________                                    

EXAMPLE 3 ##STR82## Step 3.1 ##STR83##

Under a nitrogen atmosphere, 0.05 mol of sodium1-bromo-3,5-difluorophenoxide is introduced into 50 ml of DMEU, and themixture is heated to 50° C. 0.05 ml of 1-bromo-2,2-difluoroethane isadded dropwise with stirring. The mixture is subsequently stirred at 50°C. overnight. 0.005 mol of 1-bromo-2,2-difluoroethane is added, and themixture is stirred at 70° C. for a further 24 hours. The mixture isallowed to cool to room temperature, water is added, and the mixture issubjected to conventional work-up.

Step 3.2 ##STR84##

0.03 mol of p-trans-[4-propylcyclohexyl]-2-fluorophenylboronic acid in60 ml of toluene is added to 4.8 g of NaOH in 30 ml of water, and themixture is stirred at 45° C. for 0.5 hour. 0.03 mol of1-(2,2-difluoroethoxy)-4-bromo-2,6-difluorobenzene and 0.7 g oftetrakis(triphenylphosphine)palladium(0) are added to the solution, andthe mixture is stirred at 100° C. overnight. The mixture is cooled toroom temperature, and the organic phase is separated off. The solvent isremoved in a rotary evaporator, and the residue is filtered through asilica gel fritt with petroleum ether 50-70°. The filtrate isevaporated, and the residue is crystallized from n-hexane. C 56 N 97.2I; Δn=+0.139; Δε=12.34

The following compounds of the formula ##STR85## are preparedanalogously:

    ______________________________________                                        R     ---(A.sup.1 - Z.sup.1).sub.m -A.sup.2 - Z.sup.2 -                                               L.sup.1                                               ______________________________________                                          C.sub.2 H.sub.5                                                                                             H TR86##                                         - C.sub.2 H.sub.5                                                                                          F TR87##                                         - n-C.sub.3 H.sub.7                                                                                        H TR88##                                         - n-C.sub.4 H.sub.9                                                                                        H TR89##                                         - n-C.sub.4 H.sub.9                                                                                        F TR90##                                         - n-C.sub.5 H.sub.11                                                                                       H TR91##                                         - n-C.sub.5 H.sub.11                                                                                       F C 35 N 102.5 I; Δn =  +0.136;                                       Δε = 11.07                           - n-C.sub.6 H.sub.13                                                                                       H TR93##                                         - n-C.sub.6 H.sub.13                                                                                       F TR94##                                         - n-C.sub.3 H.sub.7                                                                                        H TR95##                                         - n-C.sub.3 H.sub.7                                                                                        F TR96##                                         - n-C.sub.5 H.sub.11                                                                                       H TR97##                                         - n-C.sub.5 H.sub.11                                                                                       FSTR98##                                      ______________________________________                                    

EXAMPLE 4 ##STR99## Step 4.1 ##STR100##

0.085 mol of sodium 4-bromo-2-fluorophenoxide is dissolved in 100 l of1,3-dimethyl-2-imidazolidinone, the solution is heated to 140° C., and0.09 mol of 2,2,2-trifluoroethyl methanesulphonate is added dropwise.The solution is stirred at 140° C. for 24 hours. 500 ml of ice water aresubsequently added, and the mixture is subjected to conventionalwork-up.

Step 4.2 ##STR101##

0.05 mol of trans-n-pentylcyclohexyl-2-fluorophenylboronic acid, 20 mlof toluene, 10 ml of ethanol, 0.030 mol of Na₂ CO₃ and 0.86 mol oftetrakis(triphenylphosphine)palladium(0) are added to 0.015 mol of4-bromo-2-fluorophenyl 2,2,2-trifluoroethyl ether, and the mixture isrefluxed for 2 hours. 100 ml of petroleum ether (40-80°) are added, andthe mixture is subjected to conventional work-up.

Step 4.3 ##STR102##

13.5 mmol of diisopropylamine are added dropwise at -20° C. to 13.5 mmolof BuLi (15% in n-hexane) in 10 ml of THF. The solution is subsequentlystirred for 10 minutes and added dropwise at -40° C. under a protectivegas to a mixture of 10 ml of THF and 13.5 mmol oftrans-n-pentylcyclohexyl-2-fluorophenyl-2-fluorophenyl2,2,2-trifluoroethyl ether. The mixture is stirred first at -40° C. for0.5 hour and subsequently at room temperature overnight and then themixture is subjected to conventional work-up. C 48 N 96.6 I, Δn=0.144;Δε8.24

The following compounds of the formula: ##STR103## are preparedanalogously to Example 3 by boronic acid coupling:

    ______________________________________                                        R     Y            L.sup.1                                                    ______________________________________                                        C.sub.2 H.sub.5                                                                     OCH.sub.2 CF.sub.3                                                                         H                                                            C.sub.2 H.sub.5 OCH.sub.2 CF.sub.3 F                                          n-C.sub.3 H.sub.7 OCH.sub.2 CF.sub.3 F C 84 N (79.1) I; Δn =                                   +0.132;                                                   Δε = 14.16                                                   n-C.sub.4 H.sub.9 OCH.sub.2 CF.sub.3 H                                        n-C.sub.4 H.sub.9 OCH.sub.2 CF.sub.3 F                                        n-C.sub.5 H.sub.11 OCH.sub.2 CF.sub.3 H                                       n-C.sub.5 H.sub.11 OCH.sub.2 CF.sub.3 F C 41 N 88.9 I; Δn =                                    +0.127;                                                   Δε = 14.29                                                   n-C.sub.6 H.sub.13 OCH.sub.2 CF.sub.3 H                                       n-C.sub.6 H.sub.13 OCH.sub.2 CF.sub.3 F                                       n-C.sub.3 H.sub.7 CHF.sub.2 H                                                 n-C.sub.3 H.sub.7 CHF.sub.2 F C 73 N (31.5) I; Δn = +0.135;                                        Δε = 14.91                           n-C.sub.5 H.sub.11 CHF.sub.2 H                                                n-C.sub.5 H.sub.11 CHF.sub.2 F C 53 N (44.8) I; Δn = +0.134;                                       Δε = 14.18                           n-C.sub.2 H.sub.5 OCH.sub.2 CF.sub.2 CHF.sub.2 H                              n-C.sub.2 H.sub.5 OCH.sub.2 CF.sub.2 CHF.sub.2 F C 62 N (22.5) I;                                    Δn = +0.111;                                        Δε = 17.7                                                    n-C.sub.3 H.sub.7 OCH.sub.2 CF.sub.2 CHF.sub.2 H                              n-C.sub.3 H.sub.7 OCH.sub.2 CF.sub.2 CHF.sub.2 F C 66 N 66.7 I;                                      Δn = +0.126;                                        Δε = 17.94                                                   n-C.sub.5 H.sub.11 OCH.sub.2 CF.sub.2 CHF.sub.2 H                             n-C.sub.5 H.sub.11 OCH.sub.2 CF.sub.2 CHF.sub.2 F C 59 N 72.1 I;                                     Δn = +0.122;                                        Δε = 17.07                                                   C.sub.2 H.sub.5 OCH.sub.2 CF.sub.2 CHFCF.sub.3 H                              C.sub.2 H.sub.5 OCH.sub.2 CF.sub.2 CHFCF.sub.3 F C 63 I; Δn =                                  +0.093; Δε = 19.42                       n-C.sub.3 H.sub.7 OCH.sub.2 CF.sub.2 CHFCF.sub.3 H                            n-C.sub.3 H.sub.7 OCH.sub.2 CF.sub.2 CHFCF.sub.3 F C 59 N (47.1) I;                                  Δn = +0.094;                                        Δε = 19.6                                                    n-C.sub.5 H.sub.11 OCH.sub.2 CF.sub.2 CHFCF.sub.3 H                           n-C.sub.5 H.sub.11 OCH.sub.2 CF.sub.2 CHFCF.sub.3 F C 35 N 51.7 I;                                   Δn = +0.105;                                        Δε = 18.49                                                   n-C.sub.3 H.sub.7 OCF.sub.2 CHF.sub.2                                         n-C.sub.3 H.sub.7 OCF.sub.2 CHF.sub.2 F C 68 N 102.7 I; Δn =                                   +0.133;                                                   Δε = 11.11                                                   n-C.sub.5 H.sub.11 OCF.sub.2 CHF.sub.2 H                                      n-C.sub.5 H.sub.11 OCF.sub.2 CHF.sub.2 F                                      C.sub.2 H.sub.5 OCH.sub.2 C.sub.2 F.sub.5 H                                   C.sub.2 H.sub.5 OCH.sub.2 C.sub.2 F.sub.5 F C 36 S.sub.A (36) N 52.7 I;                              Δn = +0.110;                                        Δε = 14.8                                                    n-C.sub.3 H.sub.7 OCH.sub.2 C.sub.2 F.sub.5 H                                 n-C.sub.3 H.sub.7 OCH.sub.2 C.sub.2 F.sub.5 F C 41 N 82 I; Δn =                                +0.127;                                                   Δε = 14.84                                                   n-C.sub.5 H.sub.11 OCH.sub.2 C.sub.2 F.sub.5 H                                n-C.sub.5 H.sub.11 OCH.sub.2 C.sub.2 F.sub.5 F C 40 S.sub.B (15)                                     S.sub.A (38) N 88.6 I;                                    Δn = +0.121; Δε = 14.09                                n-C.sub.3 H.sub.7 OCH.sub.2 C.sub.3 F.sub.7 H                                 n-C.sub.3 H.sub.7 OCH.sub.2 C.sub.3 F.sub.7 F C 37 S.sub.B 27 S.sub.A                                92 N 100.8 I;                                             Δn = +0.112; Δε = 13.29                                n-C.sub.5 H.sub.11 OCH.sub.2 C.sub.3 F.sub.7 H                                n-C.sub.5 H.sub.11 OCH.sub.2 C.sub.3 F.sub.7 F C 29 S.sub.B 47 S.sub.A                               85 N 99 I;                                                Δn =+ 0.111; Δε = 13.17                                C.sub.2 H.sub.5 OCHF.sub.2 H C -2 N 44.1 I; Δn = +0.124;                   Δε = 10.21                                                   C.sub.2 H.sub.5 OCHF.sub.2 F                                                  n-C.sub.3 H.sub.7 OCHF.sub.2 H C 18 N 86.4 I; Δn = +0.136;                                         Δε = 10.79                           n-C.sub.3 H.sub.7 OCHF.sub.2 F C 42 N 54.1 I; Δn = +0.130;                                         Δε = 13.48                           n-C.sub.5 H.sub.11 OCHF.sub.2 H C 26 N 92.7 I; Δn = +0.133;                                        Δε = 10.14                           n-C.sub.5 H.sub.11 OCHF.sub.2 F C 47 N 67 I; Δn = +0.124;                                          Δε = 13.44                           C.sub.2 H.sub.5 OC.sub.2 F.sub.5 H C 160 N 225.4 I; Δn = 0.125;                                    Δε = 12.21                           C.sub.2 H.sub.5 OC.sub.2 F.sub.5 F                                            n-C.sub.3 H.sub.7 OC.sub.2 F.sub.5 H C 58 S.sub.B 69 S.sub.A 71 N 106.1                              I;                                                        Δn = +0.137, Δε = 12.0                                 n-C.sub.3 H.sub.7 OC.sub.2 F.sub.5 F C 65 N 92.5 I; Δn = +0.128;                                   Δε = 16.01                           n-C.sub.5 H.sub.11 OC.sub.2 F.sub.5 H C 43 N 109.6 I; Δn =                                     +0.127,                                                   Δε = 11.23                                                   n-C.sub.5 H.sub.11 OC.sub.2 F.sub.5 F C 58 N 100.4 I; Δn =                                     +0.124;                                                   Δε = 15.22                                                   n-C.sub.3 H.sub.7 O(CH.sub.2).sub.3 CF.sub.3 H                                n-C.sub.3 H.sub.7 O(CH.sub.2).sub.3 CF.sub.3 F                                n-C.sub.5 H.sub.11 O(CH.sub.2).sub.3 CF.sub.3 H                               n-C.sub.5 H.sub.11 O(CH.sub.2).sub.3 CF.sub.3 F                               C.sub.2 H.sub.5 OCH═CF.sub.2 H C 24 N 41.2 I; Δn = 0.137;                                      Δε = 8.79                            C.sub.2 H.sub.5 OCH═CF.sub.2 H C 9 N 36.7 I; Δn = +0.133;                                      Δε = 14.53                           n-C.sub.3 H.sub.7 OCH═CF.sub.2 H C 35 N 90.1 I; Δn = 0.150;                                    Δε = 8.41                            n-C.sub.3 H.sub.7 OCH═CF.sub.2 F C 36 N 80.7 I; Δn = +0.146;                                   Δε = 13.82                           n-C.sub.5 H.sub.11 OCH═CF.sub.2 F C 21 N 90.4 I; Δn = +0.142;          Δε = 13.47                                                   n-C.sub.3 H.sub.7 OCF═CF.sub.2 H                                          n-C.sub.3 H.sub.7 OCF═CF.sub.2 F                                          n-C.sub.5 H.sub.11 OCF═CF.sub.2 H                                         n-C.sub.5 H.sub.11 OCF═CF.sub.2 F                                         n-C.sub.3 H.sub.7 CF═CF--CF.sub.3 H                                       n-C.sub.3 H.sub.7 CF═CF--CF.sub.3 F C 76 N 101.6 I; Δn =                                   +0.153;                                                   Δε = 22.29                                                   n-C.sub.5 H.sub.11 CF═CF--CF.sub.3 H                                      n-C.sub.5 H.sub.11 CF═CF--CF.sub.3 F C 61 N 103.2 I; Δn =                                  +0.150;                                                   Δε = 21.96                                                 ______________________________________                                    

EXAMPLE 5 ##STR104##

0.05 mol of 1-trifluoromethoxy-2-fluoro-4-bromobenzene and 0.05 mol of4-(trans-4-propylcyclohexyl-2-fluorophenylboronic acid are dissolved in125 ml of toluene and 50 ml of ethanol, and 0.6 g oftetrakis(triphenylphosphine)palladium(0) and Na₂ CO₃ solution (15.9 g ofNa₂ CO₃ in 60 ml of H₂ O) are added successively. The mixture isrefluxed for 3 hours, and allowed to cool to room temperature, and theorganic phase is separated off. The aqueous phase is extracted withtoluene, and the combined organic extracts are subsequently subjected toconventional work-up. C 42 N 64.5 I; Δn=+0.125; Δε=12.55

The following compounds of the formula: ##STR105## are preparedanalogously

    ______________________________________                                        R        Y      L.sup.1                                                       ______________________________________                                        C.sub.2 H.sub.5                                                                        OCF.sub.3                                                                            H        C 31 N (26.6) I; Δn = +0.116,                       Δε = 12.07                                                   C.sub.2 H.sub.5 OCF.sub.3 F C 60 I; Δn = +0.107, Δε                              = 16.2                                                 n-C.sub.3 H.sub.7 OCF.sub.3 F C 61 N(38.4) I; Δn = +0.109,                                         Δε = 16.11                           n-C.sub.5 H.sub.11 OCF.sub.3 H C 23 N 74.2 I; Δn = +0.124,                                         Δε = 11.55                           n-C.sub.5 H.sub.11 OCF.sub.3 F C 22 N 56 I; Δn = +0.109,                   Δε = 15.6                                                    n-C.sub.6 H.sub.13 OCF.sub.3 H                                                n-C.sub.6 H.sub.13 OCF.sub.3 F                                                C.sub.2 H.sub.5 CF.sub.3 H                                                    C.sub.2 H.sub.5 CF.sub.3 F                                                    n-C.sub.3 H.sub.7 CF.sub.3 H                                                  n-C.sub.3 H.sub.7 CF.sub.3 F C 79 I; Δn = +0.115; Δε                              = 22.23                                               nC.sub.5 H.sub.11 CF.sub.3 H                                                  n-C.sub.5 H.sub.11 CF.sub.3 F C 56 I; Δn = +0.107; Δ.epsilon                             . = 20.94                                            ______________________________________                                    

Mixture Examples

EXAMPLE M1

    ______________________________________                                        PCH-7F      6.0%      Clearing point [° C.]:                                                               75                                          CCP-2OCF.sub.2.F.F 8.0% Δn [589 nm, 20° C.]: +0.0932                                                CCP-3OCF.sub.2.F.F 10.0% Δ.epsi                                        lon. [1 kHz, 20° C.]: 9.5                                               CCP-5OCF.sub.2.F.F 8.0% V.sub.(10,0,2                                        0) [V]: 1.26                                CCP-20CF.sub.3 12.0%                                                          CCP-3OCF.sub.3 13.0%                                                          CCP-4OCF.sub.3 5.0%                                                           CCP-5OCF.sub.3 7.0%                                                           CGU-2-F 15.0%                                                                 CGU-3-F 10.0%                                                                 CGU-5-F 6.0%                                                                ______________________________________                                    

EXAMPLE M2

    ______________________________________                                        CCP-2OCF.sub.2.F.F                                                                        16.0%     Clearing point [° C.]:                                                               86                                          CCP-3OCF.sub.2.F.F 11.0% Δn [589 nm, 20° C.]: +0.0930                                               CCP-5OCF.sub.2.F.F 10.0% Δ.epsi                                        lon. [1 kHz, 20° C.]: 10.8                                              CCP-2OCF.sub.3.F 15.0% V.sub.(10,0,20                                        ) [V]: 1.24                                 CCP-3OCF.sub.3.F 11.0%                                                        CCP-5OCF.sub.3.F 13.0%                                                        CGU-2-F 9.0%                                                                  CGU-3-F 7.0%                                                                  CGU-5-F 8.0%                                                                ______________________________________                                    

EXAMPLE M3

    ______________________________________                                        PCH-7F      13.0%     Clearing point [° C.]:                                                               64                                          CCP-2OCF.sub.2.F.F 6.0% Δn [589 nm, 20° C.]: +0.0888                                                CCP-3OCF.sub.2.F.F 6.0% Δ.epsil                                        on. [1 kHz, 20° C.]: 10.8                                               CCP-5OCF.sub.2.F.F 5.0% V.sub.(10,0,2                                        0) [V]: 1.32                                CCP-2OCF.sub.3 10.0%                                                          CCP-3OCF.sub.3 9.0%                                                           CCP-4OCF.sub.3 9.0%                                                           CCP-5OCF.sub.3 9.0%                                                           CGU-2-F 11.0%                                                                 CGU-3-F 11.0%                                                                 CGU-5-F 11.0%                                                               ______________________________________                                    

EXAMPLE M4

    ______________________________________                                        PCH-7F      4.0%      Clearing point [° C.]:                                                               66                                          CCP-2OCF.sub.2.F.F 20.0% Δn [589 nm, 20° C.]: +0.0950                                               CCP-3OCF.sub.2.F.F 20.0% Δ.epsi                                        lon. [1 kHz, 20° C.]: 11.2                                              CCP-5OCF.sub.2.F.F 20.0% V.sub.(10,0,                                        20) [V]: 1.07                               CGU-2-F 10.0%                                                                 CGU-3-F 14.0%                                                                 CGU-5-F 12.0%                                                               ______________________________________                                    

EXAMPLE M5

    ______________________________________                                        PCH-7F      4.0%      Clearing point [° C.]:                                                               57                                          CCP-2OCF.sub.2.F.F 20.0% Δn [589 nm, 20° C.]: +0.0943                                               CCP-3OCF.sub.2.F.F 19.0% Δ.epsi                                        lon. [1 kHz, 20° C.]: 10.1                                              CCP-5OCF.sub.2.F.F 15.0% V.sub.(10,0,                                        20) [V]: 0.97                               CGU-2-F 16.0%                                                                 CGU-3-F 14.0%                                                                 CGU-5-F 12.0%                                                               ______________________________________                                    

EXAMPLE M6

    ______________________________________                                        CCP-2OCF.sub.2.F.F                                                                        15.0%     Clearing point [° C.]:                                                               77                                          CCP-3OCF.sub.2.F.F 12.0% Δn [589 nm, 20° C.]: +0.1016                                               CCP-2OCF.sub.3 10.0% Δε                                         [1 kHz, 20° C.]: 10.4                                                  CCP-3OCF.sub.3 9.0% V.sub.(10,0,20)                                          [V]: 1.18                                   CCP-4OCF.sub.3 5.0%                                                           CCP-5OCF.sub.3 7.0%                                                           CGU-2-F 14.0%                                                                 CGU-3-F 11.0%                                                                 CGU-5-F 9.0%                                                                  BCH-3F.F 8.0%                                                               ______________________________________                                    

EXAMPLE M7

    ______________________________________                                        PCH-7F      3.0%      Clearing point [° C.]:                                                               85                                          CCP-2OCF.sub.2.F.F 17.0% Δn [589 nm, 20° C.]: +0.0966                                               CCP-3OCF.sub.2.F.F 16.0% Δ.epsi                                        lon. [1 kHz, 20° C.]: 10.5                                              CCP-5OCF.sub.2.F.F 10.0% V.sub.(10,0,                                        20) [V]: 1.19                               CCP-3OCF.sub.2.F 13.0%                                                        CCP-5OCF.sub.2.F 13.0%                                                        CGU-2-F 10.0%                                                                 CGU-3-F 10.0%                                                                 CGU-5-F 8.0%                                                                ______________________________________                                    

EXAMPLE M8

    ______________________________________                                        PCH-7F     3.0%     Clearing point [° C.]:                                                                +81                                          CCP-2OCF.sub.2.F.F 20.0% Δn [589 nm, 20° C.]: +0.0872                                              CCP-3OCF.sub.2.F.F 14.0% Δ.epsil                                       on. [1 kHz, 20° C.]: +9.7                                               CCP-50CF.sub.2.F.F 9.0% V.sub.(10,0,20                                       ) [V]: 1.25                                  CCP-2OCF.sub.3.F 21.0%                                                        CCP-3OCF.sub.3.F 12.0%                                                        CCP-5OCF.sub.3.F 6.0%                                                         CGU-2-F 11.0%                                                                 CGU-3-F 2.0%                                                                  CGU-5-F 2.0%                                                                ______________________________________                                    

EXAMPLE M9

    ______________________________________                                        PCH-7F     3.0%     Clearing point [° C.]:                                                                +79                                          CCP-2OCF.sub.2.F.F 20.0% Δn [589 nm, 20° C.]: +0.0873                                              CCP-3OCF.sub.2.F.F 13.0% Δ.epsil                                       on. [1 kHz, 20° C.]: +9.8                                               CCP.50CF2.F.F 8.0% V.sub.(10,0,20)                                           [V]: 1.21                                    CCP-2OCF.sub.3.F 21.0%                                                        CCP-3OCF.sub.3.F 12.0%                                                        CCP-5OCF.sub.3.F 7.0%                                                         CGU-2-F 12.0%                                                                 CGU-3-F 2.0%                                                                  CGU-5-F 2.0%                                                                ______________________________________                                    

EXAMPLE M10

    ______________________________________                                        CCP-20CF.sub.3                                                                           2.0%     Clearing point [° C.]:                                                                +95                                          CCP-30CF.sub.3 3.0% Δn [589 nm, 20° C.]; +0.1341                 BCH-2F.F 10.0% V.sub.(10,0,20) [V]: 1.42                                      BCH-3F.F 10.0%                                                                BCH-5F.F 9.0%                                                                 FET-2CL 6.0%                                                                  FET-3CL 6.0%                                                                  CCP-30CF.sub.3.F 10.0%                                                        CCP-50CF.sub.3.F 10.0%                                                        CGU-2-F 9.0%                                                                  CGU-3-F 8.0%                                                                  CGU-5-F 8.0%                                                                  CBC-33F 5.0%                                                                  CBC-53F 4.0%                                                                ______________________________________                                    

EXAMPLE M11

    ______________________________________                                        CCP-20CF.sub.2.F.F                                                                       8.0%     Clearing point [° C.]:                                                                +64                                          CCP-30CF.sub.2.F.F 8.0% Δn [589 nm, 20° C.]: +0.1045                                               CCP-50CF.sub.2.F.F 7.0% V.sub.(10,0,20                                       ) [V]: 1.04                                  CCP-20CF.sub.3.F 6.0%                                                         CCP-30CF.sub.3.F 7.0%                                                         CCP-50CF.sub.3.F 7.0%                                                         CGU-2-F 13.0%                                                                 CGU-3-F 14.0%                                                                 CGU-5-F 13.0%                                                                 BCH-3F.F 4.0%                                                                 BCH-3F.F 6.0%                                                                 BCH-5F.F 7.0%                                                               ______________________________________                                    

EXAMPLE M12

    ______________________________________                                        CCP-20CF.sub.3                                                                           4.0%      Clearing point [° C.]:                                                               +95                                          CCP-30CF.sub.3 3.0% Δn [589 nm, 20° C.]: +0.1088                 BCH-2F.F 5.0% V.sub.(10,0,20) [V]: 1.42                                       BCH-3F.F 5.0%                                                                 BCH-5F.F 5.0%                                                                 CCP-20CF.sub.3.F 15.0%                                                        CCP-30CF.sub.3.F 15.0%                                                        CCP-50CF.sub.3.F 15.0%                                                        CGU-2-F 10.0%                                                                 CGU-3-F 9.0%                                                                  CGU-5-F 8.0%                                                                  CBC-33F 3.0%                                                                  CBC-53F 3.0%                                                                ______________________________________                                    

EXAMPLE M13

    ______________________________________                                        CCP-20CF.sub.2.F.F                                                                       20.0%    Clearing point [° C.]:                                                                +84                                          CCP-30CF.sub.2.F.F 13.0% Δn [589 nm, 20° C.]: +0.0912                                              CCP-50CF.sub.2.F.F 7.0% V.sub.(10,0,20                                       ) [V]: 1.28                                  CCP-20CF.sub.3.F 21.0%                                                        CCP-30CF.sub.3.F 12.0%                                                        CCP-50CF.sub.3.F 7.0%                                                         CGU-2-F 12.0%                                                                 CGU-3-F 4.0%                                                                  CGU-5-F 4.0%                                                                ______________________________________                                    

EXAMPLE M14

    ______________________________________                                        PCH-7F     6.0%     Clearing point [° C.]:                                                                121                                          PCH-302 2.0% Δn [589 nm, 20° C.]: +0.0903                        CCP-20CF.sub.3 6.0% V.sub.(10,0,20) [V]: 1.90                                 CGP-CF3 6.0%                                                                  CCP-40CF.sub.3 6.0%                                                           CCP-50CF.sub.3 6.0%                                                           ECCP-3F.F 7.0%                                                                ECCP-5F.F 8.0%                                                                CGU-3-F 7.0%                                                                  CGU-5-F 7.0%                                                                  CCP-30CF.sub.2.F.F 10.0%                                                      CCP-50CF.sub.2.F.F 10.0%                                                      CP-30CF.sub.3 5.0%                                                            CP-50CF.sub.3 6.0%                                                            CCPC-33 3.0%                                                                  CCPC-34 4.0%                                                                ______________________________________                                    

EXAMPLE M15

    ______________________________________                                        PCH-6F      4.0%     Clearing point [° C.]:                                                               +113                                         PCH-7F 4.0% Δn [589 nm, 20° C.]: +0.0942                         CGU-5-F 4.0% V.sub.(10,0,20) [V]: 2.07                                        PCH-301 4.0%                                                                  CCP-20CF.sub.3 4.0%                                                           CCP-30CF.sub.3 4.0%                                                           CCP-40CF.sub.3 4.0%                                                           CCP-50CF.sub.3 4.0%                                                           ECCP-3F.F 7.0%                                                                ECCP-5F.F 7.0%                                                                ECCP-30CF.sub.3 4.0%                                                          ECCP-50CF.sub.3 4.0%                                                          ECCP-3F 3.0%                                                                  ECCP-5F 3.0%                                                                  BCH-3F.F 3.0%                                                                 BCH-5F.F 3.0%                                                                 CCP-20CF.sub.2.F.F 4.0%                                                       CCP-30CF.sub.2.F.F 4.0%                                                       CCP-50CF.sub.2.F.F 5.0%                                                       CCP-20CF.sub.3.F 4.0%                                                         CCP-30CF.sub.3.F 4.0%                                                         CCP-50CF.sub.3.F 4.0%                                                         CBC-33F 3.0%                                                                  CBC-53F 3.0%                                                                  CBC-55F 3.0%                                                                ______________________________________                                    

EXAMPLE M16

    ______________________________________                                        PCH-7F     7.0%     Clearing point [° C.]:                                                                +77                                          CCH-303 2.0% Δn [589 nm, 20° C.]: +0.0906                        CCH-501 2.0% V.sub.(10,0,20) [V]: 1.40                                        CCP-20CF.sub.2.F.F 6.0%                                                       CCP-30CF.sub.2.F.F 6.0%                                                       CCP-50CF.sub.2.F.F 6.0%                                                       CCP-20CF.sub.3 8.0%                                                           CCP-30CF.sub.3 9.0%                                                           CCP-40CF.sub.3 9.0%                                                           CCP-50CF.sub.3 9.0%                                                           CGU-2-F 11.0%                                                                 CGU-3-F 9.0%                                                                  CGU-5-F 9.0%                                                                  ECCP-3F.F 3.0%                                                                ECCP-5F.F 4.0%                                                              ______________________________________                                    

EXAMPLE M17

    ______________________________________                                        CGU-3-F    10.0%    Clearing point [° C.]:                                                                +98                                          CGU-5-F 10.0% Δn [589 nm, 20° C.]: +0.1027                       CCP-20CF.sub.3 5.0% V.sub.(10,0,20) [V]: 1.34                                 CCP-30CF.sub.3 6.0%                                                           CCP-40CF.sub.3 5.0%                                                           CCP-50CF.sub.3 6.0%                                                           ECCP-3F.F 4.0%                                                                ECCP-5F.F 3.0%                                                                CUP-3F.F 10.0%                                                                CUP-5F.F 10.0%                                                                CCP-20CF.sub.2.F.F 5.0%                                                       CCP-30CF.sub.2.F.F 5.0%                                                       CCP-50CF.sub.2.F.F 5.0%                                                       CP-30CF.sub.3 8.0%                                                            CP-50CF.sub.3 8.0%                                                          ______________________________________                                    

EXAMPLE M18

    ______________________________________                                        CCP-2F.F.F 13.0%    Clearing point [° C.]:                                                                +85                                          CCP-3F.F.F 13.0% Δn [589 nm, 20° C.]: +0.0913                    CCP-5F.F.F 10.0% Δε [1 kHz, 20° C.]: 10.9                CCP-20CF.sub.2.F.F 5.0% V.sub.(10,0,20) [V]: 1.23                             CCP-30CF.sub.2.F.F 9.0%                                                       CCP-50CF.sub.2.F.F 7.0%                                                       CCP-30CF.sub.3 11.0%                                                          CCP-50CF.sub.3 9.0%                                                           CGU-2-F 8.0%                                                                  CGU-3-F 9.0%                                                                  CGU-5-F 6.0%                                                                ______________________________________                                    

EXAMPLE M19

    ______________________________________                                        CCP-20CF.sub.2.F.F                                                                       11.0%    Clearing point [° C.]:                                                                +85                                          CCP-30CF.sub.2.F.F 11.0% Δn [589 nm, 20° C.]: +0.0997                                              CCP-50CF.sub.2.F.F 7.0% V.sub.(10,0,20                                       ) [V]: 1.24                                  CCP-20CF.sub.3.F 11.0%                                                        CCP-30CF.sub.3.F 12.0%                                                        CCP-50CF.sub.3.F 15.0%                                                        CGU-2-F 6.0%                                                                  CGU-3-F 10.0%                                                                 CGU-5-F 10.0%                                                                 BCH-3F.F 7.0%                                                               ______________________________________                                    

EXAMPLE M20

    ______________________________________                                        CCP-2F.F.F 11.0%    Clearing point [° C.]:                                                                +64                                          CCP-3F.F.F 14.0% Δn [589 nm, 20° C.]: +0.0954                    CCP-5F.F.F 6.0% V.sub.(10,0,20) [V]: 1.02                                     CCP-20CF.sub.2.F.F 6.0%                                                       CCP-30CF.sub.2.F.F 7.0%                                                       CCP-30CF.sub.3 8.0%                                                           CCP-50CF.sub.3 5.0%                                                           CGU-2-F 12.0%                                                                 CGU-3-F 14.0%                                                                 CGU-5-F 11.0%                                                                 BCH-3F.F 6.0%                                                               ______________________________________                                    

EXAMPLE M21

    ______________________________________                                        CCP-2F.F.F 17.0%    Clearing point [° C.]:                                                                +80                                          CCP-3F.F.F. 12.0% Δn [589 nm, 20° C.]: +0.0874                   CCP-5-F.F.F 11.0% V.sub.(10,0,20) [V]: 1.19                                   CCP-20CF.sub.2.F.F 6.0%                                                       CCP-30CF.sub.2.F.F 6.0%                                                       CCP-50CF.sub.2.F.F 10.0%                                                      CCP-20CF.sub.3 9.0%                                                           CCP-30CF.sub.3 2.0%                                                           CCP-50CF.sub.3 7.0%                                                           CGU-2-F 10.0%                                                                 CGU-3-F 4.0%                                                                  CGU-5-F 6.0%                                                                ______________________________________                                    

EXAMPLE M22

    ______________________________________                                        PCH-7F     9.0%     Clearing point [° C.]:                                                                +81                                          CCH-301 6.0% Δn [589 nm, 20° C.]: +0.0734                        CCH-303 6.0% V.sub.(10,0,20) [V]: 1.72                                        CCH-501 6.0%                                                                  CGU-2-F 3.0%                                                                  CCP-20CF.sub.2.F.F 9.0%                                                       CCP-30CF.sub.2.F.F 9.0%                                                       CCP-50CF.sub.2.F.F 13.0%                                                      CCP-30CF.sub.3.F 15.0%                                                        CCP-50CF.sub.3.F 14.0%                                                        CP-30CF.sub.3 5.0%                                                            CP-50CF.sub.3 5.0%                                                          ______________________________________                                    

EXAMPLE M23

    ______________________________________                                        CCP-2.F.F.F                                                                              13.0%    Clearing point [° C.]:                                                                +80                                          CCP-3.F.F.F 13.0% Δn [589 nm, 20° C.]: +0.0908                   CCP-5.F.F.F 10.0% V.sub.(10,0,20) [V]: 1.18                                   CCP-2OCF.sub.2.F.F 7.0%                                                       CCP-3OCF.sub.2.F.F 7.0%                                                       CCP-5OCF.sub.2.F.F 7.0%                                                       CCP-3OCF.sub.3 11.0%                                                          CCP-5OCF.sub.3 7.0%                                                           CGU-2-F 11.0%                                                                 CGU-3-F 8.0%                                                                  CGU-5-F 6.0%                                                                ______________________________________                                    

EXAMPLE 24

    ______________________________________                                        PCH-7F     9.0%     Clearing point [° C.]:                                                                +70                                          CCP-20CF.sub.2.F.F 13.0% Δn [589 nm, 20° C.]: +0.0855                                              CCP-30CF.sub.2.F.F 14.0% Δ.epsil                                       on. [1 kHz, 20° C.]: 9.3                                                CCP-50CF.sub.2.F.F 15.0% V.sub.(10,0,2                                       0) [V]: 1.22                                 CCP-20CF.sub.3.F 17.0%                                                        CCP-30CF.sub.3.F 7.0%                                                         CCP-50CF.sub.3.F 7.0%                                                         CGU-2-F 10.0%                                                                 CGU-3-F 5.0%                                                                  CGU-5-F 3.0%                                                                ______________________________________                                    

EXAMPLE 25

    ______________________________________                                        PCH-7F     9.0%     Clearing point [° C.]:                                                                +81                                          CCP-2OCF.sub.2.F.F 20.0% Δn [589 nm, 20° C.]: +0.1007                                              CCP-3OCF.sub.2.F.F 15.0% Δ.epsil                                       on. [1 kHz, 20° C.]: 1.23                                               CCP-5OCF.sub.2.F.F 15.0%                    CCP-2OCF.sub.3 5.0%                                                           CCP-3OCF.sub.3 5.0%                                                           CGU-3-OXF 15.0%                                                               CGU-5-OXF 16.0%                                                             ______________________________________                                    

EXAMPLE M26

    ______________________________________                                        PCH-7F    5.0%      Clearing point [° C.]:                                                               +65                                           CUP-2F.F 4.0% Δn [589 nm, 20° C.]: +0.1066                       CUP-3F.F 3.0% Δε [1 kHz, 20° C.]: 1.19                   CCP-2OCF.sub.3 8.0%                                                           CCP-3OCF.sub.3 8.0%                                                           CCP-4OCF.sub.3 8.0%                                                           CCP-5OCF.sub.3 7.0%                                                           BCH-2F.F 8.0%                                                                 BCH-3F.F 8.0%                                                                 BCH-5F.F 8.0%                                                                 CGU-2-F 11.0%                                                                 CGU-3-F 11.0%                                                                 CGU-5-F 11.0%                                                               ______________________________________                                    

EXAMPLE M27

    ______________________________________                                        PCH-301   7.0%      Clearing point [° C.]:                                                               +67                                           PCH-302FF 15.0% Δn [589 nm, 20° C.]: +0.0811                     PCH-502FF 18.0% Δε [1 kHz, 20° C.]: 1.96                 CCP-302FF 10.0%                                                               CCP-502FF 10.0%                                                               CCP-21FF 12.0%                                                                CCP-31FF 10.0%                                                                CCH-34 4.0%                                                                   CCH-35 4.0%                                                                   CCH-301 5.0%                                                                  CCH-303 5.0%                                                                ______________________________________                                    

EXAMPLE M28

    ______________________________________                                        CCP-3OCF.sub.2.F.F                                                                       7.0%     Clearing point [° C.]:                                                                +72                                          CCP-5OCF.sub.2.F.F 6.0% Δn [589 nm, 20° C.]: +0.1070                                               CCP-2OCF.sub.3.F 10.0% Δ.epsilon                                       . [1 kHz, 20° C.]: 10.7                                                 CCP-3OCF.sub.3.F 8.0% V.sub.(10,0,20)                                        [V]: 1.12                                    CCP-5OCF.sub.3.F 14.0%                                                        CGU-2-F 10.0%                                                                 CGU-3-F 14.0%                                                                 CGU-5-F 12.0%                                                                 BCH-2F.F 5.0%                                                                 BCH-3F.F 6.0%                                                                 BCH-5F.F 8.0%                                                               ______________________________________                                    

EXAMPLE M29

    ______________________________________                                        PCH-7F    2.0%      Clearing point [° C.]:                                                               +65                                           CCP-2F.F.F 10.0% Δn (589 nm, 20° C.]: +0.0936                    CCP-3F.F.F 10.0%                                                              CCP-5F.F.F 7.0%                                                               CCP-2OCF.sub.3 7.0%                                                           CCP-3OCF.sub.3 7.0%                                                           CCP-4OCF.sub.3 7.0%                                                           CCP-5OCF.sub.3 7.0%                                                           CGU-2-F 14.0%                                                                 CGU-3-F 13.0%                                                                 CGU-5-F 13.0%                                                                 BCH-3F.F 3.0%                                                               ______________________________________                                    

EXAMPLE M30

    ______________________________________                                        PCH-302   2.0%      Clearing point [° C.]:                                                               +93                                           CCH-303 7.0% Δn [589 nm, 20° C.]: +0.0768                        CCH-501 7.0% V.sub.(10,0,20) [V]: 1.77                                        CCP-2OCF.sub.3 6.0%                                                           CCP-3OCF.sub.3 7.0%                                                           CCP-4OCF.sub.3 6.0%                                                           CCP-5OCF.sub.3 7.0%                                                           ECCP-3F.F 10.0%                                                               ECCP-5F.F 10.0%                                                               CGU-3-F 3.0%                                                                  CGU-5-F 3.0%                                                                  CCP-2F.F.F 10.0%                                                              CCP-3F.F.F 11.0%                                                              CCP-5F.F.F 11.0%                                                            ______________________________________                                    

EXAMPLE M31

    ______________________________________                                        CCH-35     3.0%     Clearing point [°C.]:                                                                 +80                                          CCP-2F.F.F 6.0% Δn [589 nm, 20° C.]: +0.0930                     CCP-3F.F.F 8.0% Δε [1 kHz, 20° C.]: 11.0                 CCP-5F.F.F 4.0% V.sub.(10,0,20) [V]: 1.20                                     CCP-2OCF.sub.2.F.F 14.0%                                                      CCP-3OCF.sub.2.F.F 8.0%                                                       CCP-5OCF.sub.2.F.F 14.0%                                                      CCP-3OCF.sub.3 7.0%                                                           CCP-5OCF.sub.3 7.0%                                                           CGU-2-F 10.0%                                                                 CGU-3-F 10.0%                                                                 CGU-5-F 9.0%                                                                ______________________________________                                    

EXAMPLE M32

    ______________________________________                                        PCH-7F     2.0%     Clearing point [° C.]:                                                                +69                                          CCP-2OCF.sub.2.F.F 20.5% Δn [589 nm, 20° C.]: +0.0900                                              CCP-3OCF.sub.2.F.F 10.0% Δ.epsil                                       on. [1 kHz, 20° C.]: 10.4                                               CCP-5OCF.sub.2.F.F 7.0% V.sub.(10,0,20                                       ) [V]: 1.13                                  CCP-2OCF.sub.3.F 21.0%                                                        CCP-3OCF.sub.3.F 9.0%                                                         CCP-5OCF.sub.3.F 3.5%                                                         CGU-2-F 13.0%                                                                 CGU-3-F 9.0%                                                                  CGU-5-F 5.0%                                                                ______________________________________                                    

EXAMPLE M33

    ______________________________________                                        PCH-7F    4.0%      Clearing point [° C.]:                                                               +65                                           CCP-2F.F.F 10.0% Δn [589 nm, 20° C.]: +0.0937                    CCP-3F.F.F 10.0% V.sub.(10,0,20) [V]: 1.32                                    CCP-5F.F.F 7.0%                                                               CCP-2OCF.sub.3 7.0%                                                           CCP-3OCF.sub.3 7.0%                                                           CCP-4OCF.sub.3 7.0%                                                           CCP-5OCF.sub.3 3.5%                                                           CGU-2-F 12.0%                                                                 BCH-2F.F 12.0%                                                                BCH-3F.F 10.5%                                                                PCH-302 10.0%                                                               ______________________________________                                    

EXAMPLE M34

    ______________________________________                                        CCP-2F.F.F                                                                              10.0%     Clearing point [° C.]:                                                               +76                                           CCP-3F.F.F 10.0% Δn [589 nm, 20° C.]: +0.0936                    CCP-5F.F.F 7.0% V.sub.(10,0,20) [V]: 1.32                                     CCP-2OCF.sub.3 7.0%                                                           CCP-3OCF.sub.3 7.0%                                                           CCP-4OCF.sub.3 7.0%                                                           CCP-5OCF.sub.3 4.0%                                                           CGU-2-F 12.5%                                                                 BCH-2F.F 12.5%                                                                BCH-3F.F 12.5%                                                                CCH-35 5.5%                                                                   CCH-303 5.5%                                                                ______________________________________                                    

EXAMPLE M35

    ______________________________________                                        CGU-2-F    10.0%    Clearing point [° C.]:                                                                +10.0                                        CGU-3-F 10.0% Δn [589 nm, 20° C.]: +0.1027                       CGU-5-F 10.0% V.sub.(10,0,20) [V]: 1.30                                       CCP-2F.F.F 5.0%                                                               CCP-3F.F.F 5.0%                                                               CCP-5F.F.F 5.0%                                                               CCP-3OCF.sub.3 5.0%                                                           CCP-4OCF.sub.3 5.0%                                                           CCP-5OCF.sub.3 5.0%                                                           CCP-2OCF.sub.2.F.F 9.0%                                                       CCP-3OCF.sub.2.F.F 8.0%                                                       CCP-5-OCF.sub.2.F.F 8.0%                                                      ECCP-3F.F 6.0%                                                                CBC-33F 3.0%                                                                  CBC-53F 3.0%                                                                  CBC-55F 3.0%                                                                ______________________________________                                    

EXAMPLE M36

    ______________________________________                                        CCP-2F.F.F 14.0%    Clearing point [° C.]:                                                                +59                                          CCP-3F.F.F 13.0% Δn [589 nm, 20° C.]: +0.0900                    CCP-5F.F.F 8.0% Δε [1 kHz, 20° C.]: 11.5                 CCP-2OCF.sub.2.F.F 10.0% V.sub.(10,0,20) [V]: 0.97                            CCP-3OCF.sub.2.F.F 8.0%                                                       CCP-3OCF.sub.3 9.0%                                                           CGU-2-F 14.0%                                                                 CGU-3-F 13.0%                                                                 CGU-5-F 11.0%                                                               ______________________________________                                    

EXAMPLE M37

    ______________________________________                                        CCP-2OCF.sub.3                                                                          5.0%      Clearing point [° C.]:                                                               +94                                           CCP-3OCF.sub.3 6.0% Δn [589 nm, 20° C.]: +0.0903                 CCP-4OCF.sub.3 5.0% V.sub.(10,0,20) [V]: 1.42                                 CCP-5OCF.sub.3 6.0%                                                           CGU-2-F 6.0%                                                                  CGU-3-F 6.0%                                                                  CGU-5-F 6.0%                                                                  CCP-2F.F.F 16.0%                                                              CCP-3F.F.F 16.0%                                                              CCP-5F.F.F 16.0%                                                              ECCP-3F.F 4.0%                                                                ECCP-5F.F 4.0%                                                                CBC-33F 4.0%                                                                ______________________________________                                    

EXAMPLE M38

    ______________________________________                                        PCH-7F     8.0%     Clearing point [° C.]:                                                                +77                                          CCH-301 5.0% Δn [589 nm, 20° C.]: +0.0729                        CCH-303 5.0% V.sub.(10,0,20) [V]: 1.59                                        CCH-501 6.0%                                                                  CGU-2-F 3.0%                                                                  CCP-2OCF.sub.3 4.0%                                                           CCP-3OCF.sub.3 5.0%                                                           CCP-4OCF.sub.3 4.0%                                                           CCP-5OCF.sub.3 5.0%                                                           CCP-2OCF.sub.2.F.F. 8.0%                                                      CCP-3OCF.sub.2.F.F 8.0%                                                       CCP-5OCF.sub.2.F.F 11.0%                                                      CCP-3F.F.F 14.0%                                                              CCP-5F.F.F 14.0%                                                            ______________________________________                                    

EXAMPLE M39

    ______________________________________                                        PCH-7F     3.0%     Clearing point [° C.]:                                                                +91                                          PCH-302 4.0% Δn [589 nm, 20° C.]: +0.0791                        CCH-303 6.0% V.sub.(10,0,20) [V]: 1.80                                        CCH-501 6.0%                                                                  CCP-2OCF.sub.3 5.0%                                                           CCP-3OCF.sub.3 6.0%                                                           CCP-4OCF.sub.3 5.0%                                                           CCP-5OCF.sub.3 6.0%                                                           ECCP-3F.F 10.0%                                                               ECCP-5F.F 9.0%                                                                CGU-3-F 3.0%                                                                  CGU-5-F 2.0%                                                                  CCP-2F.F.F 8.0%                                                               CCP-3F.F.F 8.0%                                                               CCP-5F.F.F 8.0%                                                               CCP-2OCF.sub.2.F.F 3.0%                                                       CCP-3OCF.sub.2.F.F 3.0%                                                       CCP-5OCF.sub.2.F.F 3.0%                                                       CBC-33F 2.0%                                                                ______________________________________                                    

EXAMPLE M40

    ______________________________________                                        PCH-7F     2.5%     Clearing point [° C.]:                                                                074                                          CCH-35 4.0% Δn [589 nm, 20° C.]: +0.0871                         CCP-2F.F.F 8.0% V.sub.(10,0,20) [V]: 1.27                                     CCP-3F.F.F 9.5%                                                               CCP-5F.F.F 5.0%                                                               CCP-2OCF.sub.2.F.F 15.0%                                                      CCP-3OCF.sub.2.F.F 10.5%                                                      CCP-5OCF.sub.2.F.F 12.5%                                                      CCP-3OCF.sub.3 4.5%                                                           CCP-5OCF.sub.3 4.5%                                                           CGU-2-F 12.0%                                                                 CGU-3-F 7.0%                                                                  CGU-5-F 5.0%                                                                ______________________________________                                    

EXAMPLE M41

    ______________________________________                                        PCH-7F     4.0%     Clearing point [° C.]:                                                                +69                                          CCH-35 5.0% Δn [589 nm, 20° C.]: +0.0861                         CCP-2F.F.F 7.0% V.sub.(10,0,20) [V]: 1.21                                     CCP-3F.F.F 9.0%                                                               CCP-5F.F.F 5.0%                                                               CCP-2OCF.sub.2.F.F 15.0%                                                      CCP-3OCF.sub.2.F.F 9.0%                                                       CCP-5OCF.sub.2.F.F 13.0%                                                      CCP-3OCF.sub.3 3.0%                                                           CCP-5OCF.sub.3 3.0%                                                           CGU-2-F 10.0%                                                                 GGU-3-F 10.0%                                                                 CGU-5-F 7.0%                                                                ______________________________________                                    

EXAMPLE M42

    ______________________________________                                        CCP-2F.F.F                                                                              10.0%     Clearing point [° C.]:                                                               +65                                           CCP-3F.F.F 10.0% Δn [589 nm, 20° C.]: +0.1051                    CCP-5F.F.F 5.0% V.sub.(10,0,20) [V]: 1.15                                     CCP-2OCF.sub.3 6.0%                                                           CCP-3OCF.sub.3 6.0%                                                           CCP-4OCF.sub.3 6.0%                                                           CCP-5OCF.sub.3 5.0%                                                           CGU-2-F 14.0%                                                                 CGU-3-F 13.0%                                                                 CGU-5-F 13.0%                                                                 BCH-3F.F 6.0%                                                                 FT-5.FCI 6.0%                                                               ______________________________________                                    

EXAMPLE M43

    ______________________________________                                        PCH-7F     1.0%     Clearing point [° C.]:                                                                +65                                          CCP-2F.F.F 10.0% Δn [589 nm, 20° C.]: +0.0935                    CCP-3F.F.F 10.0% V.sub.(10,0,20) [V]: 1.12                                    CCP-5F.F.F 7.0%                                                               CCP-2OCF.sub.3 6.5%                                                           CCP-3OCF.sub.3 7.0%                                                           CCP-4OCF.sub.3 6.5%                                                           CCP-5OCF.sub.3 7.0%                                                           CGU-2-F 14.0%                                                                 CGU-3-F 14.0%                                                                 CGU-5-F 14.0%                                                                 CCP-3OCF.sub.2.F.F 3.0%                                                     ______________________________________                                    

EXAMPLE M44

    ______________________________________                                        CCP-2F.F.F 13.0%    Clearing point [° C.]:                                                                +61                                          CCP-3F.F.F 13.0% Δn [589 nm, 20° C.]: +0.0909                    CCP-5F.F.F 8.0% V.sub.(10,0,20) [V]: 0.99                                     CCP-2OCF.sub.2.F.F. 10.0%                                                     CCP-3OCF.sub.2.F.F 8.0%                                                       CCP-3OCF.sub.3 6.0%                                                           CCP-5OCF.sub.3 4.0%                                                           CGU-2-F 14.0%                                                                 CGU-3-F 13.0%                                                                 CGU-5-F 11.0%                                                               ______________________________________                                    

EXAMPLE M45

    ______________________________________                                        CCP-2F.F.F 13.0%    Clearing point [° C.]:                                                                +79                                          CCP-3F.F.F 13.0% Δn [589 nm, 20° C.]: 0.0910                     CCP-5F.F.F 10.0% V.sub.(10,0,20) [V]: +1.18                                   CCP-2OCF.sub.2.F.F 7.0%                                                       CCP-3OCF.sub.2.F.F 7.0%                                                       CCP-5OCF.sub.2.F.F 5.0%                                                       CCP-3OCF.sub.3 12.0%                                                          CCP-5OCF.sub.3 7.0%                                                           CGU-2-F 11.0%                                                                 CGU-3-F 9.0%                                                                  CGU-5-F 6.0%                                                                ______________________________________                                    

EXAMPLE M46

    ______________________________________                                        PCH-7F     5.5%     Clearing point [° C.]:                                                                +79                                          CCP-2OCF.sub.2.F.F 14.0% Δn [589 nm, 20° C.]: +0.0930                                              CCP-3OCF.sub.2.F.F 9.0% Δ.epsilo                                       n. [1 kHz, 20° C.]: 11.2                                                CCP-5OCF.sub.2.F.F 6.5% V.sub.(10,0,20                                       ) [V]: 1.16                                  CCP-2OCF.sub.3.F 16.0%                                                        CCP-3OCF.sub.3.F 10.0%                                                        CCP-5OCF.sub.3.F 7.0%                                                         CGU-2-O1DT 16.0%                                                              CGU-3-O1DT 8.0%                                                               CGU-5-O1DT 8.0%                                                             ______________________________________                                    

EXAMPLE M47

    ______________________________________                                        PCH-7F     5.5%     Clearing point [° C.]:                                                                +76                                          CCP-2OCF.sub.2.F.F 17.0% Δn [589 nm, 20° C.]: +0.0925                                              CCP-3OCF.sub.2.F.F 9.0% Δ.epsilo                                       n. [1 kHz, 20° C.]: 11.2                                                CCP-5OCF.sub.2.F.F 6.0% V.sub.(10,0,20                                       ) [V]: 1.16                                  CCP-2OCF.sub.3.F 18.0%                                                        CCP-3OCF.sub.3.F 8.0%                                                         CCP-5OCF.sub.3.F 3.0%                                                         CGU-2-O1DT 17.0%                                                              CGU-3-O1DT 8.5%                                                               CGU-5-O1DT 8.0%                                                             ______________________________________                                    

EXAMPLE M48

    ______________________________________                                        PCH-5F      2.80%     Clearing point [° C.]:                                                               +102                                        CCP-2OCF.sub.2.F.F 14.91% Δε [1 kHz, 20° C.]: 11.3       CCP-3OCF.sub.2.F.F 14.00% V.sub.(10,0,20) [V]: 1.02                           CCP-5OCF.sub.2.F.F 14.91% K.sub.1 [10.sup.-12 N, 20° C.]: 10.4                                            CUP-2F.F 4.69% K.sub.3 /K.sub.1 :                                            1.40                                        CUP-3F.F 4.69%                                                                CBC-33F 4.69%                                                                 CBC-53F 4.69%                                                                 CBC-55F 4.62%                                                                 CGU-2-O1DT 30.00%                                                           ______________________________________                                    

Comparative Example M48-1

    ______________________________________                                        PCH-5F      2.80%     Clearing point [° C.]:                                                               +110                                        CCP-2OCF.sub.2.F.F 14.91% Δε [1 kHz, 20° C.]:                                              +11.5                                       CCP-3OCF.sub.2.F.F 14.00% V.sub.(10,0,20) [V]:   1,11                         CCP-5OCF.sub.2.F.F 14.91% K.sub.1 [10.sup.-12 N, 20° C.]: 12.7                                            CUP-2F.F 4.69% K.sub.3 /K.sub.1 :                                            1.20                                        CUP-3F.F 4.69%                                                                CBC-33F 4.69%                                                                 CBC-53F 4.69%                                                                 CBC-55F 4.62%                                                                 CGU-3-O1DT 30.00%                                                           ______________________________________                                    

Comparative Example M48-2

    ______________________________________                                        PCH-5F      2.80%     Clearing point [° C.]:                                                               +113                                        CCP-2OCF.sub.2.F.F 14.91% Δε [1 kHz, 20° C.]: 11.2       CCP-3OCF.sub.2.F.F 14.00% V.sub.(10,0,20) [V]: 1.14                           CCP-5OCF.sub.2.F.F 14.91% K.sub.1 [10.sup.-12 N, 20° C.]: 12.9                                            CUP-2F.F 4.69% K.sub.3 /K.sub.1 :                                            1.23                                        CUP-3F.F 4.69%                                                                CBC-33F 4.69%                                                                 CBC-53F 4.69%                                                                 CBC-55F 4.62%                                                                 CGU-5-O1DT 30.00%                                                           ______________________________________                                    

EXAMPLE M49

    ______________________________________                                        PCH-5F      4.2%      Clearing point [° C.]:                                                               +84                                         PCH-7F 4.2% Δε [1 kHz, 20° C.]: 9.7                      CCP-2OCF.sub.3 4.2% V.sub.(10,0,20) [V]: 1.08                                 CCP-3OCF.sub.3 5.6% K.sub.1 [10.sup.-12 N, 20° C.]: 10.2                                                  CCP-5OCF.sub.3 4.9% K.sub.3 /K.sub.1                                         : 1.50                                      ECCP-3F.F 7.7%                                                                ECCP-5F.F 7.7%                                                                BCH-3F.F 4.2%                                                                 CUP-3F.F 4.9%                                                                 CUP5F.F 4.2%                                                                  CCP-3OCF.sub.2.F.F 4.9%                                                       CCP-5OCF.sub.2.F.F 7.7%                                                       CBC-33F 2.8%                                                                  CBC-53F 2.8%                                                                  CGU-2-O1DT 30.0%                                                            ______________________________________                                    

Comparative Example M49-1

    ______________________________________                                        PCH-5F      4.2%      Clearing point [° C.]:                                                               +92                                         PCH-7F 4.2% Δε [1 kHz, 20° C.]: 9.8                      CCP-2OCF.sub.3 4.2% V.sub.(10,0,20) [V]: 1.19                                 CCP-3OCF.sub.3 5.6% K.sub.1 [10.sup.-12 N, 20° C.]: 12.5                                                  CCP-5OCF.sub.3 4.9% K.sub.3 /K.sub.1                                         : 1.22                                      ECCP-3F.F 7.7%                                                                ECCP-5F.F 7.7%                                                                BCH-3F.F 4.2%                                                                 CUP-3F.F 4.9%                                                                 CUP5F.F 4.2%                                                                  CCP-3OCF.sub.2.F.F 4.9%                                                       CCP-5OCF.sub.2.F.F 7.7%                                                       CBC-33F 2.8%                                                                  CBC-53F 2.8%                                                                  CGU-3-O1DT 30.0%                                                            ______________________________________                                    

Comparative Example M49-2

    ______________________________________                                        PCH-5F      4.2%      Clearing point [° C.]:                                                               +95                                         PCH-7F 4.2% Δε [1 kHz, 20° C.]: 9.6                      CCP-2OCF.sub.3  4.2% V.sub.(10,0,20) [V]: 1.21                                CCP-3OCF.sub.3  5.6% K.sub.1 [10.sup.-12 N, 20° C.]: 12.6                                                 CCP-5OCF.sub.3  4.9% K.sub.3                                                 /K.sub.1 : 1.26                             ECCP-3F.F 7.7%                                                                ECCP-5F.F 7.7%                                                                BCH-3F.F 4.2%                                                                 CUP-3F.F 4.9%                                                                 CUP5F.F 4.2%                                                                  CCP-3OCF.sub.2.F.F 4.9%                                                       CCP-5OCF.sub.2.F.F 7.7%                                                       CBC-33F 2.8%                                                                  CBC-53F 2.8%                                                                  CGU-5-O1DT 30.0%                                                            ______________________________________                                    

EXAMPLE M50

    ______________________________________                                        PCH-5F      2.80%     Clearing point [° C.]:                                                               81                                          CCP-2OCF.sub.2.F.F 14.91% Δε [1 kHz, 20° C.]: 10.1       CCP-3OCF.sub.2.F.F 14.00% V.sub.(10,0,20) [V]: 0.98                           CCP-5OCF.sub.2.F.F 14.91% K.sub.1 [10.sup.-12 N, 20° C.]: 8.8                                             CUP-2F.F 4.69% K.sub.3 /K.sub.1 :                                            1.30                                        CUP-3F.F 4.69%                                                                CBC-33F 4.69%                                                                 CBC-55F 4.69%                                                                 CGU-2-F 30.00%                                                              ______________________________________                                    

Comparative Example

    ______________________________________                                        PCH-5F      2.80%     Clearing point [° C.]:                                                               +93                                         CCP-2OCF.sub.2.F.F 14.91% Δε [1 kHz, 20° C.]: 10.6       CCP-3OCF.sub.2.F.F 14.00% V.sub.(10,0,20) [V]: 1.02                           CCP-5OCF.sub.2.F.F 14.91% K.sub.1 [10.sup.-12 N, 20° C.]: 9.9                                             CUP-2F.F 4.69% K.sub.3 /K.sub.1 :                                            1.52                                        CUP-3F.F 4.69%                                                                CBC-33F 4.69%                                                                 CBC-53F 4.69%                                                                 CBC-55F 4.62%                                                                 CGU-3-F 30.00%                                                              ______________________________________                                    

Comparative Example M50-2

    ______________________________________                                        PCH-5F      2.80%     Clearing point [° C.]:                                                               +98                                         CCP-2OCF.sub.2.F.F 14.91% Δε [1 kHz, 20° C.]: 10.2       CCP-3OCF.sub.2.F.F 14.00% V.sub.(10,0,20) [V]: 1.08                           CCP-5OCF.sub.2.F.F 14.91% K.sub.1 [10.sup.-12 N, 20° C.]: 10.7                                            CUP-2F.F 4.69% K.sub.3 /K.sub.1 :                                            1.40                                        CUP-3F.F 4.69%                                                                CBC-33F 4.69%                                                                 CBC-53F 4.69%                                                                 CBC-55F 4.62%                                                                 CGU-5-F 30.00%                                                              ______________________________________                                    

EXAMPLE M51

    ______________________________________                                        PCH-5F      4.2%      Clearing point [° C.]:                                                               +67                                         PCH-7F 4.2% Δε [1 kHz, 20° C.]: 9.0                      CCP-2OCF.sub.3 4.2% V.sub.(10,0,20) [V]: 1.04                                 CCP-3OCF.sub.3  5.6% K.sub.1 [10.sup.-12 N, 20° C.]: 8.7                                                  CCP-5OCF.sub.3  4.9% K.sub.1                                                 [10.sup.-12 N, 20° C.]: 8.7                                             ECCP-3F.F 7.7% K.sub.3 /K.sub.1 :                                            1.27                                        ECCP-5F.F 7.7%                                                                BCH-3F.F 4.2%                                                                 CUP-3F.F 4.9%                                                                 CUP-5F.F 4.2%                                                                 CCP-3OCF.sub.2.F.F 4.9%                                                       CCP-5OCF.sub.2.F.F 7.7%                                                       CBC-33F 2.8%                                                                  CBC-53F 2.8%                                                                  CGU-2-F 30.0%                                                               ______________________________________                                    

Comparative Example M51-1

    ______________________________________                                        PCH-5F      4.2%      Clearing point [° C.]:                                                               +78                                         PCH-7F 4.2% Δε [1 kHz, 20° C.]: 9.5                      CCP-2OCF.sub.3  4.2% V.sub.(10,0,20) [V]: 1.09                                CCP-3OCF.sub.3  5.6% K.sub.1 [10.sup.-12 N, 20° C.]: 10.1                                                 CCP-5OCF.sub.3  4.9% K.sub.3                                                 /K.sub.1 : 1.44                             ECCP-3F.F 7.7%                                                                ECCP-5F.F 7.7%                                                                BCH-3F.F 4.2%                                                                 CUP-3F.F 4.9%                                                                 CUP-5F.F 4.2%                                                                 CCP-3OCF.sub.2.F.F 4.9%                                                       CCP-5OCF.sub.2.F.F 7.7%                                                       CBC-33F 2.8%                                                                  CBC-53F 2.8%                                                                  CGU-3-F 30.0%                                                               ______________________________________                                    

Comparative Example M51-2

    ______________________________________                                        PCH-5F      4.2%      Clearing point [° C.]:                                                               +82                                         PCH-7F 4.2% Δε [1 kHz, 20° C.]: 9.1                      CCP-2OCF.sub.3  4.2% V.sub.(10,0,20) [V]: 1.15                                CCP-3OCF.sub.3  5.6% K.sub.1 [10.sup.-12 N, 20° C.]: 10.8                                                 CCP-5OCF.sub.3  4.9% K.sub.3                                                 /K.sub.1 : 1.41                             ECCP-3F.F 7.7%                                                                ECCP-5F.F 7.7%                                                                BCH-3F.F 4.2%                                                                 CUP-3F.F 4.9%                                                                 CUP-5F.F 4.2%                                                                 CCP-3OCF.sub.2.F.F 4.9%                                                       CCP-5OCF.sub.2.F.F 7.7%                                                       CBC-33F 2.8%                                                                  CBC-53F 2.8%                                                                  CGU-3-F 30.0%                                                               ______________________________________                                    

EXAMPLE M52

    ______________________________________                                        PCH-5F      3.2%      Clearing point [° C.]:                                                               +104                                        CCP-2OCF.sub.2.F.F 17.0% Δε [1 kHz, 20° C.]: 10.0                                           CCP-3OCF.sub.2.F.F 16.0% V.sub.(10,0,                                        20) [V]: 1.06                               CCP-5OCF.sub.2.F.F 17.0% K.sub.1 [10.sup.-12 N, 20° C.]: 10.2                                             CUP-2F.F 5.4% K.sub.3 /K.sub.1 :                                             1.74                                        CUP-3F.F 5.4%                                                                 CBC-33F 5.4%                                                                  CBC-53F 5.4%                                                                  CBC-55F 5.3%                                                                  CGU-3-F 20.0%                                                               ______________________________________                                    

Example M53

    ______________________________________                                        PCH-5F      3.60%     Clearing point [° C.]:                                                               +11.6                                       CCP-2OCF.sub.2.F.F 19.17% Δε [1 kHz, 20° C.]: 9.1                                           CCP-3OCF.sub.2.F.F 18.00% V.sub.(10,0                                        ,20) [V]: 1.16                              CCP-5OCF.sub.2.F.F 19.17% K.sub.1 [10.sup.-12 N, 20° C.]: 10.9                                            CUP-2F.F 6.03% K.sub.3 /K.sub.1 :                                            1.55                                        CUP-3F.F 6.03%                                                                CBC-33F 6.03%                                                                 CBC-53F 6.03%                                                                 CBC-55F 5.94%                                                                 CGU-1V-F 10.00%                                                             ______________________________________                                    

We claim:
 1. A liquid-crystalline medium based on a mixture of polarcompounds having positive dielectric anisotropy, characterized in thatit contains one or more compounds of the general formula I ##STR106## inwhich R is H, an alkyl or alkenyl radical having 1 to 15 carbon atomswhich is unsubstituted, monosubstituted by CN or CF₃ or monosubstitutedby halogen, it also being possible for one or more CH₂ groups in theseradicals to be replaced, in each case independently of one another, by--O--, --S--, ##STR107## --CO, --CO--O--, --O--CO-- or --O--CO--O-- insuch a way that O atoms are not linked directly to one another,A¹ and A²are each, independently of one another, a trans-1,4-cyclohexyleneradical in which, in addition, one or more non-adjacent CH₂ groups maybe replaced by --O--, --S--, or both, or a 1,4-cyclohexenylene radical,Z¹ and Z² are each, independently of one another, --CO--o--, --O--CO--,--CH₂ O--, --OCH₂ --, --CH₂ CH₂ --, --CH═CH--, --C.tbd.C-- or a singlebond, and one of the radicals Z¹ and Z² is alternatively --(CH₂)₄ -- or--CH═CH--CH₂ CH₂ --, Y is F, Cl, halogenated alkyl, alkenyl or alkoxyhaving 1 to 6 carbon atoms, L¹ is H or F, and m is 0or 1,and one or morecompounds selected from the group consisting of the general formulae II,III, IV, V and VI: ##STR108## in which the individual radicals are asdefined below: R⁰ is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in eachcase having up to 7 carbon atoms, X⁰ is F, Cl, halogenated alkyl,alkenyl or alkoxy having 1 to 6 carbon atoms, Y¹ and Y² are each,independently of one another, H or F, r is 0 or 1,with the provisos thata) the compounds III and IV are not identical to the compounds of theformula I, b) if L¹ is X m=1, A¹ and A² are each trans-1,4cyclohexyleneradicals, Z¹ is a single bond and Z² is --CH₂ CH₂ --, then Y is not Cl,c) if L¹ H, m=0, A² is a trans 1,4-cyclohexylene radical and Z¹ is --CH₂CH₂ --, then Y is not F, Cl, --CF₃, --OCHF₂, --CHF₂ or --OCF₃, e) if Y¹and Y² on the central phenylene ring of formula IV are F, r of formulaIV is 1, Z² of formula I is a single bond, and m=0, then Y ishalogenated alkyl, alkenyl or alkoxy having 2-6 carbon atoms.
 2. Mediumaccording to claim 1, characterized in that the proportion of compoundsof the formulae I to VI together is at least 50% by weight in the totalmixture.
 3. Medium according to claim 1, characterized in that theproportion of compounds of the formula I is from 3 to 80% by weight inthe total mixture.
 4. Medium according to claim 1, characterized in thatthe proportion of compounds of the formulae II to VI is from 20 to 80%by weight in the total mixture.
 5. Medium according to claim 1,characterized in that it contains a compound of the formula ##STR109##in which R, L¹ and Y are as defined in claim
 1. 6. Medium according toclaim 5, characterized in that Y is F, OCHF₂ or OCF₃.
 7. Mediumaccording to claim 1, characterized in that R in the compounds of theformula I is selected from the group consisting of ethyl, propyl andpentyl.
 8. Medium according to claim 1, characterized in that itcontains one or more compounds of the formula I and one or morecompounds of the formula ##STR110## in which X⁰ is F, OCF₃ or OCHF₂,R⁰is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to9 carbon atoms, and Y² is H or F.
 9. A method of using theliquid-crystalline medium according to claim 1 which comprisesincorporating said liquid-crystalline medium into an electroopticaldevice.
 10. Electrooptical liquid-crystal display containing aliquid-crystalline medium according to claim
 1. 11. Compounds of theformula I ##STR111## in which R, A¹, A², Z¹, Z², and m are as defined inclaim 1, and L¹ is H and Y is halogenated alkyl, alkenyl or alkoxyhaving 2-6 carbon atoms.
 12. Compounds of the formula ##STR112## inwhich R, Y and L¹ are as defined in claim
 1. 13. A liquid-crystallinemedium based on a mixture of polar compounds having positive dielectricanisotropy, characterized in that it contains one or more compounds ofthe general formula I ##STR113## in which R is H, an alkyl or alkenylradical having 1 to 15 carbon atoms which is unsubstituted,monosubstituted by CN or CF₃ or monosubstituted by halogen, it alsobeing possible for one or more CH₂ groups in these radicals to bereplaced, in each case independently of one another, by --O--, --S--,##STR114## --CO, --CO--O--, --O--CO-- or --O--CO--O-- in such a way thatO atoms are not linked directly to one another,A¹ and A² are each,independently of one another, a trans-1,4-cyclohexylene radical inwhich, in addition, one or more non-adjacent CH₂ groups may be replacedby --O--, --S--, or both, or a 1,4-cyclohexenylene radical, Z¹ and Z²are each, independently of one another, --CO--o--, --O--CO--, --CH₂ O--,--OCH₂ --, --CH₂ CH₂ --, --CH═CH--, --C═C-- or a single bond, and one ofthe radicals Z¹ and Z² is alternatively --(CH₂)₄ -- or --CH═CH--CH₂ CH₂--, Y is F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6carbon atoms, L¹ is H or F, and m is 0 or b 1,and one or more compoundsselected from the group consisting of the general formulae II, III, IV,V and VI: ##STR115## in which the individual radicals are as definedbelow: R⁰ is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each casehaving up to 7 carbon atoms, X⁰ is F, Cl, halogenated alkyl alkenyl oralkoxy having 1 to 6 carbon atoms, Y¹ and Y² are each, independently ofone another, H or F, r is 0or 1,with the provisos that a) the compoundIII and IV are not identical to the compounds of the formula I, b) if L¹is H, m=1, A¹ and A² are each trans-1,4-cyclohexylene radicals, Z¹ is asingle bond and Z² is CH₂ C₂ --, then Y is not Cl, c) if L¹ is H, m=0,A² is a trans-1,4-cyclohexylene radical and Z² is --CH₂ CH₂ --, then Yis not F, Cl, --CF₃, --OCHF₂, --CHF₂ or --OCF₃, and d) if Y¹ and Y² onthe central phenylene ring of formula IV are F, and r is 1, then Y ishalogenated alkyl, alkenyl or alkoxy having 2-6 carbon atoms.